Crazy to go from RS-1 to IN82?

My Dad has built a dedicated home theater in his house. The projector ceiling mount is too far back for him to use the IN82. I have an RS-1 with about 500 hours on it, and I'm starting to want more lumens (I can still change to high lamp mode). I'm thinking about selling him my RS-1, and getting the IN82 for myself. Unlike him, I don't have a dedicated home theater. My carpet is light, the ceiling is white (with a black curtain on the ceiling directly in front of the screen), black drapes on the back wall, but fairly light colored walls everywhere else. Will the increased ANSI of the DLP projector make more of a difference in a less than ideal setting, than the overall better blacks of the RS-1? In other words, in my room, will the RS-1 or the IN82 look better? Also, I don't notice rainbows on his Toshiba DLP T.V.. Does that mean I'm o.k. with this projector? As the IN82 starts to loose lumens, will black levels suffer if I start to open the Iris, or will black levels look the same as the lamp looses lumens and I open the IRis to keep the same image brightness?

Thanks,
Rick