I am surprised as to how "right" it feels to have that size screen in my room. Now I recommend to my friends to just sit closer and spend their money in quality, not size.
As far as the room dimensions, the only thing that I would change is the height - if I could only raise the house a few feet... The width was supposed to be 15', but the builder changed it to 14' on his own before I caught it (that's about 140 cu. ft. less volume). As it is now, I am about 400 cu. ft. short of the minimum recommended volume (according to the modecalc program from
www.realtraps.com), one more foot width and height would get me there.
Also, an unintended effect of being so concerned with sound-proofing my room, is that all that sound-proofing insulation in the walls and ceiling makes the room very good at retaining temperature (it's like a thermos). I am thinking about adding a dedicated ventilation system if I can do it quietly.