Topic: Roland RD-700SX
As could be expected Pianoteq plays best with its default curve:
Velocity = [0, 127; 0, 127]
Even when pressing very lightly and slowly, RD-700SX still generates MIDI velocity of 1 and one could be tempted to shift the lower end of the velocity curve to the right with one step:
Velocity = [1, 127; 0, 127]
however with that setting the instrument is behaving strangely and producing silence when expected to produce sound, that's why I am not recommending it at all. (The test is conducted while playing Chopin).
To summarize: use factory defaults of Pianoteq and RD-700SX in order to obtain the optimal dynamic response.