<EDIT>
OK- I'm going to re-phrase. (my post from last night was unclear)
I think that a 5 - 8 mm 635-636 beam is ok (you can see it better for high ariel beam-shows, for one thing) and big scanner mirrors are ok, 50kps is not needed, and everybody is too caught up in the teeny-weeny mirrors that have to have tiny little laser beams to fit them to get these high speeds. The only point that I can see for all of this is to draw cartoons on the wall which you could easily do with a 72" plasma TV or movie projector. I believe that you can have nice beams and effects at 5k. This is just my opinion fwiw. <end rant>