Even so, i had some of my own concerns. One of the patches Jan, the Bluetile developer, ships helps improve Gnome compatibility. Without it, XMonad is very hard to configure with Gnome. I repeated these concerns to him, but Jan's reaction is that he was intially unsure that all his patches would be accepted by upstream. I've noticed over the past couple of days on the XMonad mailing list, Jan has been pushing his patches one by one to upstream. So far, they are being accepted one by one, sometimes as is, sometimes with comments. Although i don't know exactly how far Jan has to go, it looks he's building a pretty good relationship with upstream, and i feel pretty confident the bluetile bits will all eventually find their way upstream.
Consider it another open source success story.