I'd suggest maybe sitting down at a real piano (grand if you can) and reacquaint yourself with what it's SUPPOSED to sound like. Perhaps you just have different expectations to the real thing.

Mind you, I tend to think the upper half octave on a 76 is just a hair too loud (but it's not too bright, IMO), compared to miking the average grand (and especially an upright) as the high strings were always furthest away from the mikes... It's something I feel on most sampled pianos I've played (I own Kurzweil, Triton, G70 as my current axes).

Quick question... Does the piano sound overly bright on style Parts to you? Or is it just you? If just you, you MIGHT just be whacking away a bit hard in that top octave or so....

Last resort is to either use a bit of maybe 10k shelf using the per-part EQ (you got that on an E60?), or maybe, if not, on the whole arranger. I sometimes think the whole thing is a bit to treble-y, especially if you are primarily doing early sixties and earlier music (those fifties disks had not much over 10-12kHz, back then!).

See if any of this helps...