I'm contemplating buying a Rev2. So I was at Guitar Center where they had a Rev2 under a Prophet 6 so I could listen to both of them. Guitar Center being what it is, I had to use headphones to be able to hear anything, so I couldn't do the best direct comparison. I spent about an hour listening and knob twisting.
A few quick observations:
Effects. The Prophet 6 really does sound nice. But, the richness and depth of a lot of sounds seems to be dependent on the effects, chorus is used a lot in the factory patches. I would guess that anytime it's using a single osc, where osc2 is used for polymod, it's going to need effects for richness and size. This reminds me of my Juno-60. Then I found the effects on the Rev2 to be more optional, the richness of those patches seemed to be mostly from stacking, or at least you can obtain it via stacking, the effects are not so much of a crutch.
Harshness. I would not call the Prophet 6 harsh, it's very smooth. The Rev2, however, can go into harsh territory. And I'm not sure it's the filter? With the filter open wide with no resonance, the harshness seems to be clearly coming from the oscillators, they are very harmonically rich and buzzy. Which is not a bad thing, it's just how they are, it's the modern synth sound we hear today. The Rev2 will cut through a mix, live or in the studio, the Prophet 6 sounds great solo but in a band context with guitars it might be buried in the mix.
Bass. The Prophet 6 has nice low end, it was definitely there in the headphones. The Rev2, the deep low end was never there, that's a big concern. Maybe through EQ you could recover it, but I'm not sure why it's missing? It sounds like someone went way too far with coupling capacitors in the analog stages, getting rid of DC, but also getting rid of way too much bass, like they just were not paying attention in the circuit design. Or someone wanted the Rev2 to lack bass, I don't understand it myself, it seems like a missed bass opportunity that would not detract from the sound of the synth, I would rather have it and choose to filter it out myself than have someone else make that choice for me.
So if I had to make a choice I'm leaning towards the Rev2, with bass recovery EQ.