purp,

I'm only using the 30K as a reference. From personal experience, that has been a good number to shoot for. Running my 1515/2.5d in my 8ight T on 5S is nuts. It has lots of power, but then on 4S, geared at about 15/48 or so, is a good race setup and does well for bashing too, without the insane power. Of all of my motors, the 1515/2.5d is my favorite.

Oh, and not to be presumptuous or anything, but if you've only messed with Feigao motors, you really can't anticipate what the performance of the Neu motors will be based on your experince with the Feigaos. If you set your system up right, heat will not be an issue with the Nue motors. I don't even take a temp gun with me any longer when I go out and run.