Your A4000 and RM1x should be compatible interms of
the 3 yamah Midi FX parameters (Choruse,Reverb,Other),
so that's a bonus, a few shortfalls with the RM1x:
1) The copy track/section etc.., commands actually just replace
the tracks with the same phrase, eg copying track 10 to track 11
just puts the same "phrase" in track11 as in track10, so editing track11
affect's track10. Same goes with sections, so you have to then
copy the "phrase" in track 10 to a new phrase and apply the phrase
to track 11, which means you have to keep note of phrases number's
etc.., and it becomes tedious.
2) In "Grid" record mode, it doesn't play the other Midi channels.
3) When you overdub a phrase, you can't jump to say bar 2 or bar 4,
you have to start at bar 1, but when you play back a phrase, there's an option
to start at bar 2 or 4 or whatever, why offer one and not the other, dunno,
this oversight bugs me because if I want to add swing to bar 2 only, I have
to then split the phrase into two then overdub the second part.
These are three oversights that sh*t me about the RM1x, oh and yeah
you can't create new beats whilst playing other beats, so this limits
it a bit for live stuff (where as the electribes allow you to do this).
Also when you switch between "songs" and stuff, there's a bit of latency
whilst the box reassign's the voices, this sh*ts alot of live performers.
But there are plenty of good things about the box - never crashes.
Heaps of knob's, turn's on quickly, "sort of" intuitive in a crazy way.
Something like 480ppq, timing is good unless it get's overloaded by
midi data then it gets out of time.
Plus a little known feature is that you can re-assign the midichannels
so they overlap, ie track1,2,3, etc, can then both go out midi-channel1.
This is actually quite handy.