Overall, I'd say DLP will give you a bit better blacks, but that's a general fact, not an iron clad truism. Given your good level of light control, either technology should give you decent blacks.
Much depends upon how far away you'll sit, the size of screen you want and what type of image you demand. SDE will generally be more noticeable with the 900U than it would be with, say, the Optoma H72. If you need to sit very close to the screen or demand a huge image, I'd say the Optoma may make you happier. It's also a bit brighter.
On the other hand, most inexpensive ($2k-ish) DPLs lack the mounting flexibility of the PT-AE900U. For example, the Panny boasts a 2:1 focus vs 1.2:1 for the Optoma. The Panny also has an excellent physical lens shift vs none for the Optoma. Lastly, some DLPs, including the H72, have large offsets that may limit where you can mount the PJ.
If you're sensitive to noise, the Panny is possibly the quietest digital projector you can buy today. The Optoma is no slouch, but is a tad louder. Probably not an issue while you're gaming, though.
Under $2k, I'd say the Mitsubishi HD1000U is another one to look at. It's bright, quiet and uses the DarkChip 2 DLP. It's about $1,500 which is pretty darned cheap for 720P.
Assuming you require 720P, it would seem the likely contenters are the Panasonic PT-AE900U, the Optoma H72 & the Mitsubishi HD1000U. There are other good ones, of course- the latest Sanyo LCD may also serve you well.
My admitted bias is for DLP, but try to watch one first. A small segment of the population is very sensitive to "rainbows," or color separation artifacts. One-chip DLPs use a spinning multisegment color wheel which can lead some people to percieve the indivual colors in a disconcerting way. Newer PJs use a 4X wheel vs the 2X wheels of older machines, but a few people still can't stand them. If you, or someone who'll be sitting with you, falls into this camp you'd be better off buying a good LCD.