I was not too worried about the compatibility as you could mix and match with wooden boxes (Certainly better than the Paradise hives which had dimensional issues) however the brood box was awkward to lift and the polystyrene was not strong enough, as propolis is stronger than the poly and bits would crack off. Bees als decided to chew their way through the split between two brood boxes making a second entrance. I too sold my Paynes.
The same "weak" polystyrene of the nucs seems to be just about OK though. However my two originals (8 framers now) are getting very tired.
I assume someone will have bought the rights/tooling for the Paynes stuff and will launch them to the world soon. (By to the world, I mean the UK as we have our own special frame sizes and would have been better sticking to Langstroth frames in the first place imo.)
May your bees read the same books as you do.