Wife acceptance factor in my case. I'd love to have a front projection DLP, and had a front projection crt/ home theater in my last house.
Front projection can be more expensive, and requires more planning. In my case, we went with DLP rear projection this time because while we like movies and high definition content, we don't want to dedicate a room to theater alone. With rear projection, as long as you don't go too large, you have most of the placement options of a regular tv set.
With front projection, you need more care in placement, lighting, wiring, selection of materials. Integrating 5.1 sound can be a challenge. People often put those da-lite and Stewart screens on the wall. Putting the speakers in front of the screen gets clumsy if you have towers, (you have to look past them.) You wouldn't want one near a window where sunlight was likely. Will you be okay with dedicating a room dark? I don't know about you, but we're always doing things to get more light, not less. But if you can dedicate a basement for example, front projection makes more sense.
Below is a picture of my old home theater. It was well planned, with lots of strong, directed lighting to illuminate the walls, while not washing out the screen. Also remember, you'll learn that your guests won't like sitting in the total darkness of your home theater forever. You need some theater lighting, on dimmers so they can see their drinks, find their way to the bathroom etc...practical concerns.
Note also, attention to acoustics, in the form of "live-end/dead-end" construction, whereby the area around the listener is acoustically live with hard reflective surfaces, but the area around the speakers is deadened with fabric covered, rigid architectural fiberglass panels and bass traps.
http://vsdrives.com/graphics/basement.jpg
