Basically I think this would simulate whether a microphone is close to the hammers or closer to the soundboard, or what characteristic you use, something like that. Though it might not even be 100% realistic I think it would be cool if one could control this.

Actually, there might be a solution to your problem, in the form of a notch filter to remove essentially the fundamental bass frequency (singular, not plural) of the piano's action noise.  Here is how I would go after it: turn the action noise as loud as it is capable of playing, and then turn DOWN the overall volume slider (but not to zero!).  This assumes you have a software parametric equalizer that is available in your DAW.  Once you instantiate the EQ, turn on the frequency analyzer of the parametric equalizer -- then play some notes, and look for the recurring bass sound that is essentially independent of whichever note you play.  Once you find the offending frequency, use the EQ to sculpt out that particular frequency and use a high value of Q to exorcise as narrow a band of sound around the offending frequency.  That's why it's called a notch filter.

If you happen not to have a sequencer/DAW that has a software parametric equalizer available, then I think one might be S.O.L.

My two cents worth,

Cheers,

Joe

Often I want more hammer noise but the hammer samples have much bass, so that resonates a lot with high resonance settings. While this might be natural, from a sound design perspective I would really like to cut the bass of the hammer samples.

Also, a selection of a few different kinds of hammer and key release samples would be cool.

Cheers