I will just say that if a voice expansion is made available, just do it. I use poly unision WAY more than I ever imagined I would, and I consider it one of the most important (yet underrated and/or unknown) features of the Rev4. I would like to see more granular detuning options once it is in PU2 mode, but the fact they added this to the synth at all was amazing.
It's of course possible to get the same results with multi tracking the default voice mode, and this was how a lot of vintage recordings achieved their sound, but to be able to push a button a few times and get that effect is the exact type of feature a modern incarnation of a vintage synth should have.