So basically it boils down to:
1. JVC RS57 w/ HP Screen (but this will kill off-angle performance)
2. Sony VW600 w/ Unity Gain Screen or StudioTek 130 for a little extra gain (would be my personal choice if I had the budget) But i don't really care about 3D as I hate wearing two pair of glasses.
Those projectors are really far apart in price though. The 600 is double the 57 so there's that.
Also, if I wasn't planning on upgrading anytime soon and had the cash, I would get the 600 so I'm futureproof on 4K, especially on that size screen.
Personally, I would get a used model at this point for less money and save and upgrade to something really really nice and 4K in a few years.
I would not consider a unity gain screen since he has "some ambient light from dining room/kitchen". A unity gain white screen needs a very well light controlled HT. I am not saying the HP is the right choice either (maybe, maybe not). Need more details on his setup (walls, ceiling, floor color/covering, seating arrangement, etc.........).