I know Stewart includes an equalizer for the centre channel with their microperf screens, probably as part of their THX certification. Both the Da-Lite and the Stewart perforated screens are supposed to be +- 1 Db out until the very high frequencies, that's theoretically undetectable... http://www.avsforum.com/ubb/smile.gif
Moire is not commonly a problem with DLP or D-ILA, the increased size of the screen door on an LCD will sometimes pose a problem though. I haven't heard of anyone having serious moire problems other than Sony 10HT users, it's probably an combination of the higher resolution and a common screen size. A Cygnus IMX de-pixelizing lens should eliminate the problem, and (of course) reduce the visibility of pixelization.
I think if your perf screen rips during installations most reasonable companies will replace it. That should be a rare occurence, the edge of the screen is usually re-inforced so a tear should only result from a flaw in the screen fabric.
What size of screen are you thinking about? 2.8 gain is a bit high if you want to avoid hotspotting.