O.K, so I can send each of the midi controllers to separate channels, and assign those channels to tracks, but I wont be able to do the MIDI note split map on just one MIDI instrument without the xrules tool? (like each of the octaves on a midi keyboard going to a separate channel, and then dropping keypresses from each channel into separate tracks).
Yeah, that's essentially it. You can "split" a MIDI controller to play multiple instruments, but a single instrument can't be controlled using multiple controllers.
There is no difference between 3.0 and 3.1 when it comes to this feature.
Renoise scripting/tools can be as surgical as we need them to be... as long as we're talking incoming "realtime MIDI" there aren't many limitations to think of.
NB: last week, I found a small issue in xRules that needs fixing, so tell me if you're interested in using a newer version of this tool.