dore_m no : sustain (All damper free) and Partial sustain (Some dampers free with several combinations) : it's the same modeling algo in Pianoteq. And it's the good way. and it work so when you side chain audio Pianoteq 8 + midi informations with an existing sample library in a DAW. No samples "sustain" "SR" soluce could work correctly. It have to be modeled. forget sampling for Sympathetic resonance (to much rules and samples). Only modeling .
Even the sympathetic Resonance option in VSL is a modeled DSP with existing close samples played : the bug is that the overtones decay is too fast (0.5 / 2 sec). it's sad because the rules of their Algo are already ok . they have just to fix/correct the release times of overtones, and the volume of the main key that produce overtones with their DSP. it's easy (they have already the model like Ivory 3) but they don't fix the overtones DSP times (that don't use additional samples, just modeling on the existing sample played).
And they can even use this fixed modeled DSP engine to produce sustain and repedaling without the use of existing sustain samples…. but they don't
Garritan CFX : don't use overtones samples to make Sympathetic resonance (just see the voices counter) it use modeled DSP …. already. But they could extend it to sustain, but no. To separate the both is an error. that's why repedaling in Garritan is not perfect. (resonance sample layer)