You might get more hits if you post this (or have the mods move it) to the regular CIH forum, I think it gets more traffic.
But the answer depends on what features you require. If you require lens memory then I think yes, it is the cheapest. Though if you keep an eye out for some B-stock JVC RS4910's they might come surprisingly close and be substantially better.
That's a tricky question, personally, a $1k projector would not be good enough for me to 3-4 years. For that sort of lifespan I'd be looking at something like an RS49. But then again, aside from my current Planar 8150, I was dropping $2-3k on a projector every year or two.