From the earliest to the latest R44's, I can't say in the real world that I have noticed a great difference in performance. The good news is that the MAUW has gone up, but so has the empty weight. If you fit the pop out float kit, you take quite a hit on payload and it isn't realistically a four person helicopter any more over any sort of range. Offhand I think the performance graphs stop at 40degC. I think you can now get air con, but I hate to think what that would do to payload in addition to the pop outs. Good luck!