All those are different speakers (from one another). At least you're keeping to the same brand which is good to match timbre across them (i.e. same sonic signature).
Ultimately it'll come down to:
1. Your budget 2. How they sound to you. Can you audition any of them before buying? 3. Aesthetic appeal
Try to eliminate some and narrow down options. I've listened to the Kefs and was impressed. Personally, having also auditioned the Emotiva T2s & C2, I would go for them, they sound amazing - and a more economical option than some (most?) of the others.
How about a studio 520C for the center, and a set of bookshelves for the rear? I seriously do not know why you would need 3 sets of top tier floorstanders, with two sets only pulling surround duty. Every man has his reasons, but just know it is way overkill for surround duties.
Theater Fusion 8100, XPA3, Dayton SA1000, SI HT 18 BIC Formula F12(2), Emo UAW 8.2 (4), Dayton Me 8.2 (4), Dayton MeC 8.2 (2) Oppo BDP 93,BenQ w1070 Elite Screen 135" AT Screen
2.1 Channel PT-100, UPA 200, JBL Studio 580, JBL Sub 550p
I see a reference to using an XPA2 for the 'low frequencies', probably of the fronts?
You won't gain anything. EACH amp will still continue to swing the entire voltage required of a full range signal. The only way to make something like this work is to go to a LINE LEVEL crossover before the amps. This restricts the frequencies required of each amp to those needed by the driver. Depending on crossover frequency you can actually Increase 'apparen't power by up to about 3db. Thats double.
Crossover frequcny plays a Large Part of the above in practice.
Magnepan MG1.6qr HSU Research VTF-2 MK3 2x Parasound A23 Parasound P5 Cambridge Audio DACMagic Plus Sony PS3 x4 @3foot runs of 10ga Belden speaker wire. GRADO SR80e on-ear headphones iMac as music server (2009) Panamax 5510 w/) ISO transformer LG 65" B6 OLED display