Wowsie, just browsed that list of components. You're sure going for redundancy upon redundancy. Seems a solid plan, although I wonder if it wouldn't be cheaper to just go mid-range setup and then simply upgrade mid-range again in a year or two. The logistics of that might be a shit storm in itself though.
You say you're going to be running two of thoose bad boys? I hope you've got enough wall amps at your hosting provider to run two huge guzzlers at peak(ing) capacity. Back of the envelope calculation, they are going to be sucking up what 7, 8 amps? I host my servers in a shared co-lo which puts a severe limit on how much juice my servers can suck up without me paying extra.
But
given you're proposing this I guess you've considered this.