You really are limited in several areas with rear projection. You do have a number of options, but they are all pricey, and may not meet your needs depending on the space.
Panasonic wins the game on this one with one of the markets only true short throw lenses which can go on a number of projectors. The obvious hit is that price is through the roof.
You didn't really state a budget though. Some can spend $10,000 per projector. Some can only spend $2,000. Others are fine to $30,000 or more. While 'cheaper is better' is always a good concept, you have to work with what your budget allows, and your budget should be based upon the size of your audience and the available funding.
Front projection can work very well if there is good line of sight from the back of the sanctuary to the screen location(s).
So, more details would be necessary to determine if front projection could work, and you still would need a place for every projector and projectors which can hit the screen size from the distance you are hoping to achieve.
How many screens/projectors?
What throw distance would you want/demand from the front?
Is that distance flexible?
What is your budget?
How flexible is that budget?
With rear projection or front projection light output of the projector you purchase is important, but depends on the lights in the room. With rear projection, you get more quality from less lumens, but still need a good starting point for both. About 80 advertised lumens, per square foot, as a minimum is a good starting point. About a 45 square foot screen, and about 3,700 lumens as a minimum.
Short throw projectors...http://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&mfg=&p=&w_m=&r=&br=&ll=<g=&t=&db=&dt=&c=&ar=&dvi=&wr=&sp=14&pjl_m=&pjw_m=&pjh_m=&td_m=&is_m=&i=d&tr=&oop=2&sort=brt&sz=15
That's a list of over 250 models which show short throw capability.
We will eliminate ones over $12,000 and eliminate ones with less than 3,200 lumens. Oh, and widescreen only. 16:9 or 16:10 aspect ratio.http://www.projectorcentral.com/projectors.cfm?g=1&hide=0&st=1&mfg=&p=500&p=12000&w_m=&r=&br=3200&br=40000&ll=<g=&t=&db=&dt=&c=&ar=Wide+%2816%3A9-10%29&dvi=&wr=&sp=14&pjl_m=&pjw_m=&pjh_m=&td_m=&is_m=&i=d&tr=&oop=2&sort=brt&sz=15
That's a more workable list.
The model right at the top is absolutely my top recommendation...http://www.projectorcentral.com/Canon-REALiS_WUX450ST.htm
You get a 120" diagonal 16:10 image with 1920x1200 resolution from about 5' away from the screen. That gives you several feet behind the projector for mounting and connections without disturbing the projector. The lens shift will help with the placement as well, which makes installation easier. The brightness is excellent for a vivid image, and perhaps can be run in low-lamp mode to lengthen the lamp life.
You still want a rear projection screen with high dispersion to help ensure an even image.
The other models...
A huge issue with most short throw models is that they have very limited throw distance and are often ultra-short throw. So, models like the Optoma units just after the Canon can only throw an image as large as 100" diagonal. They also are extremely close to the screen which makes adjustment very difficult and image uniformity is typically quite poor. They are very inexpensive, but look pretty bad.http://www.projectorcentral.com/Optoma-EH320UST.htm
Those types of ultra short throw models are designed to be used in classrooms, not for serious presentations.
There are some models which can deliver that image size and have a very low price tag...http://www.projectorcentral.com/Optoma-W316ST.htm
But, a model like that may not live up to the claimed specifications, or even come close. At under $1,000 per projector (or so), it's a great price, but whether it is bright enough and appropriate is another question, and one I would worry about.
IMO - The Canon is ideal for your setup. It's bright, hits the size you need, and delivers quality that you won't find from another model in this category for the price.
- Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.