I have played on the M3 and the PA 2x Pro. I have never touched a Triton.
The M3 keybed is pretty good (better than PA 2x and PA800)
I still think the FSX Keybed on the Tyros 2/3/4 and Motif XS/XF is cleaner and stiffer. As in - the keys don't rattle on hard release or they don't shift from side to side when u try and rub your hand over them. (not a big issue at all but if we are trying to compare apples to apples then YES there is a difference).
Honestly the PA 2x PRO felt almost identicle to the PA 800 to me... Ide say it might have been a "bit" better but it still surprised me because I have heard a lot of people comment on how good the PA 2X keybed was... I was left wondering if these people had ever laid their fingers on a Tyros /Motif XS/XF Keybed.
When I Say a keybed is spongey - its hard to explain... but I am trying to say the spring action is too soft and constant. the Tyros Keys almost have a "click" or a "snap" to them when you press them. again hard to explain but its just a more natural feel than many other keybeds.
When you press a tyros key down "black or White key" it goes all the way down even at the back up near the casing of the keyboard...
Whereas a PSR or a PA800 key just springs down from where the tips of the keys are and the back does not move. So if you press you finger lightly right up the back on the keys on the PA 800 you will find it much harder to make the key go all the way down...
hope this helps. If you go into a shop and experement on the different boards a lot of what I am saying will make more sense