One of the best sounds:
Yamaha PRS, in a house hallway, with a couple of crappy microphones.
"""It seems that no matter what piano True, SI Electric or Demension, it's like the
attack is too brittle for lack of words.....
They don't seem to fit in the mix with other "live" instruments."""
If all sound bad::: Check for clipping, your speakers, ears,....
Use voxengo span and the CW analyst to clarify what is bothering you.
use some eq on the bad frequencies.
Use the transient shaper.
The included pianos work for most all but way subtle piano work, where layers and velocity response are alone in the world.
Otherwise, after all the other 36 tracks are mixed, eq'ed, reverbed, compressed and maximized, it don't sound like no piano anyway.