I went for 2 of these 8GB kits:
8GB G.Skill DDR3 PC3-14900 1866MHz Sniper Series (9-10-9-28) Dual Channel kit
(F3-14900CL9D-8GBSR)
And I do realise that anything over 1600MHz isn't going to yield much gain in performance. Part of the reason I went for them is that they weren't that badly priced and they are on the supported memory list for the Extreme7.
2 x 8GB kits? @CL9 Wow, I think I might cancel the ones I got on order and grab some of those. How much did they set you back?