I haven't set mine all up yet (I'm at the screen stretching stage woohoo!), but I'd like to know the answer to that question, too. I have speakers with rear ports and they are happy when sitting around two feet away from the wall, but that sits them really close to the screen. I obviously don't want to see any movement in the screen. I'll have mine up tonight hopefully and I'll see how close I can get with the speakers then post back.
Video: Optoma HD3300, Panamorph UH480, Darbee Darblet, Samsung BD D6700 Blu Ray player, DIY Seymour Centerstage XD 138" Curved Screen
LCR - Tannoy DC12i, Sides - Tannoy IW63, Rears - Tannoy Saturn DC6ti Bookshelf, Ceilings - Tannoy CMS 603DC (TF), Tannoy CMS 601DC (TR), 3 Micro Marty/1 Full Marty DIY subs
Amplification: Emotiva XPA-3, Emotiva XPA-2, Outlaw Audio 7700, 2x Inuke 6000DSP
Receiver: Anthem MRX 720