Regarding the numbers game, you absolutely cannot trust the mftrs, and must instead look towards 3rd party reviews. Often, they will be done in best mode, which often means not only the best color accuracy, but in high lamp mode.
So sometimes a PJ is way brighter than a JVC, perhaps including Pana/Epson, historically. Then you calibrate them, and all of a sudden the JVC is significantly brighter. There is little brightness lost on a JVC when calibrated, comparatively, historically.
Also, JVC overstates their lumens to a much lesser degree.
3LCD and single chip DLPs for that matter are often stating their contrast with the use of a dynamic iris. JVCs simply don't use them, and don't need them. You understand how a DI works, yes?
It is IMO not worth spending the money particularly on the superior contrast of a JVC if most viewing is with lights on. It COULD be worth it for better reliability, but that's a value judgment depending on warranties in question, CMS, free bulbs, etc.
PM BMX for HD250 quote, if interested. Much less than you probably think, but I did already mention price, or maybe not. The Seymour XD is $20 per linear ft for the wide stuff, and something like $13 for the narrower stuff. You could spend $40-80 on decent to top grade wood for the frame, and some super cheap doug fir for the false wall. Well, this is similar to what I did.
IOW, you can have new screen, false wall, JVC projector, within the limit of your original budget. I too was at 15' and now at 12', with the false wall. 11.5' I believe is the guaranteed distance where you cannot discern its texture with 20/20, according to a very well known calibrator/installer, 3rd party. I for one can be much closer and still not notice.