I'm splitting my time between a P6 and a P5. I do love the Prophet 6, though it's taken effort to accept it as its own creature, and not as an almost/not quite P5. Slop has never been the key for me, and detuning the oscs doesn't bring that gorgeous blurriness of the 5 into play. But the P6 does "beautiful" quite well. And "interesting," to be sure. And it's an immensely playable synth. I've never spent so many hours just wandering the keys. I play it more than I play piano now.
The P5, however, still has the instant vibe every time I come back to it. The unevenness, the fuzziness come from an unknown place, far as my ears are concerned. The fact that I live with a P5 part of the year hasn't stopped me from wanting to buy another one. Madness, by some standards, but I hold the Prophet 5 to be one of the most beautiful instruments.
I know how fortunate I am to have both synths in my life, but there's a weird "grass is greener" twang to it all, as the P6 and P5 live several countries apart. When I'm with the P5, loving every sound that it makes, but worried that every note might be its last, I miss the P6 for its reliability and calm demeanor. When I'm with the P6, I'm running it through this chorus or that, or begging the fine tune knob to somehow fritz out and go just a bit ancient on me. Yeah, I'd love to have them in the same room, MIDI'd up together, but that's years away.
I have to say, as I've mentioned in other posts on GS, I value the tips and tricks I've learned here regarding bringing the Prophet 6 closer to home. Lowering the levels of the oscs in the mixer etc. And no matter any grumblings I have or wishes for a Prophet 5.5, I love the 6 and will never part with it. But that P5 sitting 4 feet away... damn.