I'm strongly considering an HD70, as I have an H31 and love it, and the '70 would bolt up to the same mount. But according to the many reviews I've read, the Mits is a better PJ, especially with regards to black levels and out-of-the-box color accuracy. My high regard for Optoma, coupled with the fact that the HD70 was $500 cheaper, was why I was leaning towards the '70. But at $899 I might give the '1000U a shot.
BTW, I really really love the remote w/my H31, which is nearly identical to the new HD70 remote (except for color). I especially dig the way the backlighting fades out slowly- very cool.
