If you have good airflow around the projector with no blocked vents or anything, then you really shouldn't have an issue. InFocus, I believe, has the light tunnel issues that I read about all the time, and I would expect that they may have a solution to this issue in place by now, but I can't tell you for sure. If Sheridan comes on here, he may have better information about what DLPs won't have this issue.
Color wheels are a continued issue that I hear about at least as often as I hear about LCD polarizers going bad. The newer, better LCDs use inorganic panels which help to eliminate yellowing issues. The 8500UB and AE4000 both use inorganic LCD panels.
Lots of options out there for sure, most of them are pretty darn good.