I just seen this post and that nobody has replied to it so I'l keep it simple and hopefully you'll see this post and it'll help you with the answer.
Yes, Xuen is affected by lust/warp/heroism. However! His stats are based on a snapshot. In other words, you'll want heroism to already be active, preferably also with your trinkets and pots etc all going at the same time before you pop Xuen so that he has maximal stats.
Hope this helps, and I hope this is still true! The answer was taken from wowhead (yes I'm that bored because I can't get on WoW right now haha) from a while ago so hopefully it does stand true!
Frankly, my dear. I don't give a damn.