Possible alternatives:
ClavinetV - every rompler
CMI V - free sampler plus a bit crusher
DX7V - FM8 or there are free DX series emulations, some of which even support sysex import
PianoV 2 - one of the many sampled pianos available
Buchla Easel V - Reaktor Blocks includes all the modules you would need
HOWEVER...
CMI V - comes with CMI libraries and I assume (though nobody has confirmed this for me yet) it imparts its own sound to samples
DX7V - Arturia have added extensions which expand its usefulness and have reworked the UI in interesting ways which may or may not suit you
PianoV 2 - much smaller in storage size and possibly more tweakable than sampled pianos
Easel V - is unique and would take a bit of work to replicate even with Reaktor Blocks
Clavinet V - yeah, sorry, can't think of a saving grace for this
Just my thoughts - I'd be interested to hear what others think