by sheer, scientific data, track velocity is actually less flexible as solely a means of volume control - this is definitely not an argument, just a presentation of data.
unfortunately the way it was originally presented has given it this sense of being a quick volume control, but that was never the case for anything other than a very surface level use of the mpc velocity sensitivity.
by default in os2, pads hit "harder" than they do in os1/akai os. by default in these two earlier os's, amp vel is by default 0-100, in os2 it's 50-100 (a more commonly used "default" curve for both instrumentation and percussion).
first of all, simply speaking from a velo-level perspective, this 50-100 default gives you a smaller curve of attentuation - you start high and can only go down HALF as much as in other os's unless you specify a range of 0-100. second, if you were to adjust TRACKVEL seeking to simply change the level, this will change ALL of the following:
*any PGM with filter velocity settings (vel-cutoff, suddenly your whole track will be much more lowpassed than the rest
*individual pad relative volumes in drum PGMS where you've assigned different amp vels (snare=75-100, hat=0-100, you're gonna end up with inaudible hats next to a comparative hammer snare
*simulted layers with different amp vels ala my recent technique post will change "level" at different rates when TRACK VEL is changed
*90% of ANY preset or homemade you're using from any number of hardware/software synths are going to sound different when attentuated via TRACK VEL due to all the in-house velocity modulation triggered by velocity. VERY EASILY, you could end up trying to turn down your volume for these tracks via velocity, and the only thing that happens is A, you lowpass it, or B, you turn down the LFO rate because either/or were being modified by velocity.
your w/around of adjusting a whole program affects any and all tracks containing those samples
did you read my whole post? i accounted for that with a faster, more specific solution:
so, say you have a ride track employing two rides on two pads. instead of thinking "hey, i need to turn down the volume of that track, it's too loud" think "i need to turn down those two pads." move to that track, WINDOW over the sample in the main screen, and turn them down. this is the number one usefulness of the main screen Layer Program Edit shortcut.
if you're in grid edit, say, go at it from GPE itself, and then hit window over LEVEL to go to LPE if you have layered samples to change. if not, just stay in GPE
lastly, if folks are DETERMINED to be using separate tracks for similar elements of their beat (ie all drums on different tracks), they might as well be using different PGMS for each drum sound as well - that way we can backtrack to the beginning of this thread and just let every track be TRACK MIXED since there will be no program confliction.