The SL-990 uses the TP/40 keyboard, which is actually Fatar's "big" piano action. It is still used even in newer models, albeit sometimes e.g. in an updated version with wooden keys. Apart from that, many controllers and pianos by different manufacturers use Fatar actions (e.g. Doepfer), mostly the TP/40 or the TP/100 (particularly when weight and price is a concern). So, if you are looking for a noticeably different piano action, your options are limited (but not zero).
The mentioned current Privia PX series (mainly PX-150, PX-350, PX-5) all use the same tri-sensor keyboard. It's quite precise, especially for its weight (about 12kg if I recall correctly), and its touch is, while on the light side, still not unrealistic and allows for controlled play. I own a PX-3 myself, which uses a slightly older version of the same keyboard. Since it has a lighter touch, I would recommend compensating a bit for it in Pianoteq (touch curve).
Then there is the Roland A-88. It uses Roland's own 'Ivory Feel G' keyboard, is still quite a light instrument (about 16kg?), and from what I understand the Ivory Feel G is perfectly usable (though maybe again a bit on the light side). It is a bit more expensive than the PX-150, and from what I've heard the keyboard is not that much superior to Casio's piano action, but I would strongly recommend visiting a dealer and making that determination for yourself. A lot is personal taste anyway.
The Fatar/Studiologic Numa Nero uses a 'TP/40WOOD' keyboard, which is almost the same as in the SL-990 but with wooden keys. This means it is heavier (the instrument weighs >20kg) and also probably has a heavier touch, which in my opinion actually helps pianissimo play. So it might also be an option. However, it is already quite expensive.
Last but not least: you might consider changing the touch curve in Pianoteq and see if that helps you with the SL-990.
Last edited by kalessin (16-07-2014 11:04)
Pianoteq 6 Standard (Steinway D&B, Grotrian, Petrof, Steingraeber, Bechstein, Blüthner, K2, YC5, U4, Kremsegg 1&2, Karsten, Electric, Hohner)