Apologies for the late reply - had a fair bit to do.
I'm most used to 5th, but I don't find it that hard to convert from one to the other once something's set down, so if you prefer 3.5 or w/e that's fine.
True, but Doc Smith's version of psionics is very different to the usual D&D stuff, which is why I think it might be a nice basis for something in D&D.