Qq used since months (I bought the pro version)
I also Grand3 The Imperial and the VSL
It starts without waiting time (unlike banks of sounds ..)

This app is excellent.
(Only the reverb is average for certain sounds (I removed), I use rather the SIR2 VST)

I do not like the optional electric models, not enough live (in the Velvet Protools is better for this type of sound)
Pianos, pianos, harpsichords are awesome

I play on a MP8 and uses internal 192Khz (binaural mode) and connected to an external UAD2192.