Hm. My vote is receiver. IIRC, Pro Logic uses a matrixed center. What I really mean to imply is that I think dialogue intelligibility, along with all of the other goodies (more discrete channels, better panning within front stage), would be desirable. House shaking LFE is fun and all, but dialogue + front stage will always benefit, no matter if it's action, comedy, chick flick, you name it.
20x30 needs awesome subwooferage, but one step at a time. I am just baby-stepping you for now, until the other freaks get you to refinance your home just to make movies more fun.