There's certainly a burn-in risk when using DLPs for a sim... cockpit outline, etc. But like a good plasma, a good DLP projector should have a sceensaver-like setting that will either very subtly rotate the image (a pixel at a time; you don't notice unless you're looking for it), or occasionally swapping colors (negative image).
If you've got the money, a DLP would be the best choice. The blacks are almost as good as projected celluloid.
  As far as the best goes, I attended a demo of NEC's newest units a while back, and was blown away. They've even got settings to correct for distortion when projecting on irregular surfaces: They centered the image on the corner where walls and ceiling meet, and it looked almost flat. It'll also throw onto a concave surface (even spherical) with little apparent distortion. Amazing. But not cheap. I think NEC's smallest DLP will set you back about $3000 US. But I'm not positive: I don't sell 'em, I just install 'em. And God knows I don't buy them... but trust me, they're not cheap.