IMO, if you're going with a projector it's best to make it all or nothing, especially if you have a dedicated media room. The only time it makes sense to get a drop-down screen is if you've got a living room setup and watch TV during the day on a regular TV.
Get or make a fixed screen and hang it in a good position. Even if it only weighs 4lbs., you're not going to want to move around a 130"+ screen every time you want to watch a movie.
If you're concerned about 1.78:1 vs. 2.35:1, check out the screen section on AVSforum, specifically the constant image height section. Or you could go with a masking system.