Thanks so much, it makes perfect sense. The only reason i bother people on the forum with this is that the owner's manual is very scarce in words - it simply says 5w40, that's it!! (interestingly, it doesn't even "suggest" or recommend the expensive CF moto oil kit). So that leaves much to wonder but it aligns with what you said: that in general any oil of right viscosity will do.
They don't mention AM2 or higher RPM applications, and given they provide 5 years of engine warranty, it makes me wonder, right? Anyhow, thanks so much bud. So for the 400, best to try AM2, for 1000 any car oil should do, but high rpm application "might be better". Thanks for all your contributions to the forum! My respect bro!