Questions about Osmose, MPE, and Airteq

Here is my take:
1. Most acoustic keyed instruments are non-MPE, and pianists and organists have been playing them for ages perfectly fine.
2. Guitar and similar stringed instruments are essentially acoustic MPE instruments as each finger is a direct driver of an independent string. It would be puzzling for a guitarist even to imagine hammer-ons and pull-offs not as string-scoped but as instrument-scoped actions.

Modern control surfaces like the Linnstrument, Haken Continuum, Osmose, Exquis and others are by design closer to how guitar works as each contact point of the human body with the control surface is being tracked individually. When I'm holding a chord on my Linnstrument and move just one finger horizontally it would be very unintuitive for me if it made the pitch of all the notes of the chord shift. Of course whether you even want to make these gestures would depend on the type of music you play. For traditional instrumental music this may be a rare occasion indeed, while for experimental and ambient stuff this may be more relevant. So to each their own.

As for MPE as a software feature, I frankly see no reasons why in 2026 a software synth (which is not a vintage synth emulation) would choose _not_ to have it. Per-note expression is a standard feature of VST3 and MIDI 2.0 protocols after all. Same for me for tuning systems support (like MTS-ESP) — not everyone is going to use it, but I see no reasons in not supporting it on the software architectural level. Also, the MPE stream does not have come from the human input: it may be the result of an application of a tool like this: https://www.christophek.de/MPEDrift/

Although theoretically correct, your argument doesn’t hold up in reality: if the foundation is plucked string instruments, why is MPE hardware based on keyboards?
But, moreover and above all: when a guitarist plays vibrato or bends a string, it’s very, very rare for them to be pressing down on more strings than the one they’re vibrating, because—even if only momentarily—they’re playing a solo or treating the instrument as if it were monophonic, since you don’t vibrate with just one finger; you vibrate with your whole hand.
When we see people playing MPE hardware, we see that they’re basically playing solos—at most, two parts: left hand and right hand (and for that, the split function on keyboards has always existed).
In short, I still think that MPE complicates more things than it solves, and that it responds more to marketing strategies than to musicians’ real needs, and their actual abilities

Basing Osmose on standard keyboard was imho a brilliant design choice because it allowed the keyboardists to use their muscle memory right away for like 90% or their performance, — e.g., Seabord is less intuitive in its feel to the keyboardists I believe. But if a person is not using the unique features of Osmose like continuous pressure control (that allows among others pressure-controlled portamento), wiggling and other gestures, then I'd agree that this person probably just does not really need Osmose — and there's nothing wrong with that. Some other instruments like Continuum have only one common thing with keyboards: the linear left-to-right pitch ordering. Others like Linnstrument I wouldn't even compare to keyboards but rather to a guitar (or, even closer, to tapped stringed instruments like Harpejji or Chapman stick). And they all can be used without using MPE features at all.

Actually, I totally agree with you on that the musicians that are interested in full MPE support are a minority. I'm happy to belong to this minority though;)

I liked your phrasing of the `"P" in MPE` and this made me think that actually we have very little to disagree about here. I believe the whole MPE "label" holds different meaning to different people actually. I'm a software engineer by trade, and to me the first and foremost difference of the MPE vs "non-MPE" (or, I'd put it as "pre-MPE") is an engineering design decision of having expression (pitchbend/pressure/...) data being tied to individual notes vs. to the whole note stream. Like, having the key signature next to the clef vs. having accidentals near the individual notes. But don't treat this analogy too literally: one may say that the key signatures have been invented not to be overloaded with accidentals so having accidental tied to notes is more cumbersome. This is a human perspective, humans are overwhelmed by lots of symbols. MPE standard is not for humans, but for computers, and they are perfectly fine with crunching streams of data.

Of course, such standard by design is polyphonic but it does not mean we have to truly utilize its polyphonic nature all the time. I believe - that's just my guess - that when people are looking for "MPE hardware" the primary thing that they are looking for is not polyphony or the technicalities. I guess 80% of the time people are looking not for _polyphonic_ but for _continuous_ aspect of the control. For me personally this is an extremely rewarding feeling to have direct continuous tactile connection with the sound rather than losing this control after the key press and delegating e.g. the piano hammer to do the thing for you. This does not work well with all the timbres but when it works — it delivers. And now the question: how do we properly implement such continuous control if a person wants to do such a simple gesture as gradually pressing a chord or gradually lifting fingers while pressing a chord until the chord fades out completely? Even if the person is not really intending to give each note its own individual voice. How do we choose what data to send from the control surface to the synth? The maximum of the pressure values for all currently pressed notes? The minimal value? The mean? The median? And the answer is: MPE becomes not an overcomplicated, but actually a very _natural_ way to send the data from such control surface even when polyphony is not the main goal: just send the information about what each finger does without aggregtion/simplification/loss and let the synth engine decide what to do with it. So MPE (or newer MIDI 2.0) is just a straightforward _engineering vehicle_ to perform such transmission.

Regarding Osmose/Seaboard/Continuum. I still think when say one needs to play a piano part in a song it's just better to take a normal traditional keyboard and play it in as the keyboard action suits the timbre and original physical action of the instrument. Instruments like Osmose or Continuum are rarely bought for polyphonic expression per se, they are bought for very specific physical action (and performance gestures that are enabled by this action) that suits particular, — not all, — timbres. And the instrument choice will definitely impose some artistic limitations, that's normal. I'm not that familiar with Osmose action in practice but if it is not possible to play pianissimo vibrato, well, we just have to embrace it as every instrument has it's limitations: after all, we all are used to that the piano can't bend pitch and sustain the sound indefinitely and are not asking for those qualities embracing the limitations and loving the piano for what it _can_ do for us. I have the same attitude towards my linnstrument, embracing all its quirks and leveraging all its strenghs.

the polyphonic aspect might be impossible to play live with a MPE controller, which is kind of obvious when you think about it, but it's quite easily done with software.

and probably more suited and precise than a MPE controller could ever be.

i think a MPE controller would be fine for monophonic parts, but beyond that, mostly no.

Afaik, Pianoteq is the only Modartt product which is MTS-ESP-capable.