I'd think that as long as you can get them to clock together, all will be good. Expecting much more from Yamaha's pretty stripped down MIDI implementation is optimistic, I'm afraid... (and it's not just Yamaha)

Is it just me, or has anyone else noticed the complete dumbing down of arranger MIDI capabilities over the last few years? My old RA90, and G1000 had MUCH better MIDI implementation that the G70. I can't speak for Yamaha, perhaps they've ALWAYS sucked but it's as if the manufacturers have decided that not enough people use TWO or more keyboards or modules anymore, now they have made them a bit better (but still not good enough!).

If you are having issues with connectivity, I encourage you to make a BIG noise to the dealer's manufacturer reps and tech support... Perhaps if they are woken up to the fact that there ARE many of us with more than a cheap PSR in our living rooms, they MIGHT pull their finger out of their... well, you know where!

At the very least, two different arrangers from different manufacturers should be able to synchronize clocks, and basic style division navigation... Intros, Endings, Variations and Fills. Just THAT would make assembling the perfect arranger (whatever you want THAT to be!) a MUCH easier task...