I'm very much in favour of the sort of documentation as provided in this case by Joshua's waveform examples. This evidence can be highly instructive, if interpreted with due consideration to all pertinent factors. As things stand we are not privy to all possible pertinent variables.
So, with this hard documentation as a great start, the following questions have occurred to me, as I attempt to understand these comparative illustrations:
[first, I assume from the Joshua's comments that 'his real thing', the actual acoustic piano decay recorded, is a 100-year old Chickering baby grand]
1) I assume that the environment in which the piano is located will have imprinted itself upon the resultant waveform i.e., we are not looking at the 'raw' output of the piano in isolation (which would require an anechoic chamber – with a good stout floor membrane...)
2) I assume that the Pianoteq models are 'running' consistent virtual environments as part of a meaningful comparison i.e., if a room mode or reverberation enhancement is applied to the piano engine output, this is at least loosely the same in character for the illustrated waveform examples. This would make comparison meaningful (and fair), at least for the Pianoteq 3/5 simulations.
3) In that case, we have the following consideration: To what extent does (can) the applied virtual acoustic be fairly compared to that of the Chickering's native environment? And, if the Pianoteq examples are indeed 'raw' piano engine-only, what are we to make of the comparison with the real thing, again reasonably assuming the unavoidable presence of live ambience/reverberation.
4) The convolution effect of a real acoustic upon the real piano would be generally similar to that of an electronic equivalent upon the modeled piano, in that it will colour the original significantly, though not beyond the point of recognition. That is to say, the general characteristics of the piano waveform will 'survive' the reverberation. So we can still learn 'something' even in the case of a possible slightly apples/oranges testing comparison.
These questions can of course be answered to a great degree by Joshua himself, and I would be very glad to learn more details of the recording process.
5) This whole exercise leads me to ponder what might result from a comparison of a new, mint Steinway D (or similar) and the Pianoteq 5 D4, set up and recorded in similar real/virtual environments.
Another poster, njaremko, has offered this observation:
"The decay of the D4 behaves and lasts exactly the same as my Steinway sample libraries."
The conditions under which these sample libraries, themselves, have been created, is of course a natural and essential consideration, in turn.
So I remain eager to learn more on this whole issue. For my part, I have often (from v4) deliberately held down long notes, listening to the decay – not to critique it, but to marvel at its mysterious complexity (knowing it is a synthetic creation, albeit a very sophisticated one). Real pianos, no matter how diverse in all areas of tonal generation, of course sound 'real' simply because they are real. Too many of them would do better as toxic firewood than as musical instruments, sad to say (not something I am remotely recommending, in case I have aroused unintended offence by that wry remark)...
Cheers,
Stephen.