The JVC DLA-RS15 with a Carada BW 1.4 gain screen would provide an excellent image.
http://www.projectorcentral.com/JVC-DLA-RS15-projection-calculator-pro.htm
http://www.carada.com/ProductInfo.aspx?productid=PROJECTION-SCREEN-H134C
If you can wall mount the side-surrounds then I’m thinking that you’ll want to consider multi-poles and mono-poles for the rears since it’s only 15’ wide.
It’s difficult recommending speaker/sub/receiver options without some sort of budget in mind. Your area is good sized so a dual sub setup would be advisable. How do you feel about a speaker like this that has a matching stand available?
http://www.ascendacoustics.com/pages/products/speakers/cmt340m/cmt340m.html
Are you incorpoating multi-tier seating? If so, what are the planned viewing distances?
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Random thoughts:
I think the Oppo is totally unnecessary unless you do intend to listen to SACD and DVDA. You can take that $400 savings, and put that elsewhere.
Depending on the pricing you've found on that Sony, you can pony up a bit more for the CMS with the RS20/25/35. However, you'll need to buy a colorimeter, or hire a pro.
Something that I *might* mull over is spending a lot less on PJ (for Pana/Epson, or even less than that), with the anticipation of something like a LED 3D PJ a few years from now, or something, I dunno.
If blacks and contrast are key, but perfect colors are not worth the extra couple/few grand, AND you look to keep the PJ for several years or more, the RS15 is a great suggestion. You might save even more with the RS10 as used/demo/openbox.
Lastly, Carada is known as the bang for buck value in fixed screens, but if I built an HT all over again, I'd be thinking long and hard about a DIY AT screen, with Seymour material.
The Sony will give it up with blacks to the RS15 even RS10, but will have better OTB colors. The RS20/25/35 will win in just about every category, otherwise.