Devil's Canyon has been out for over a month.
For Haswell-E/X99 September is about as official as a rumor gets since documents were leaked last month with the release schedules. They'll probably find a way to delay it again though even though samples have been all over for months now.
Are you seriously considering a Haswell E setup? You're talking well over $1500 for a CPU/Motherboard/RAM that isn't going to do anything for you that your 4770K doesn't already do...
Unless you plan on doing some serious encoding a 3570K would last you until it dies. If all you're looking for is expanding storage then any system upgrade (especially the x99 route) is just overkill. The easiest solution is obviously just find a board that supports another 9211-8i if your current board won't. If you're going to go overkill though.... you might as well skill Devil's Canyon and go straight for the big guns with Haswell E.
Yeah I mean you can certainly go overkill if you want. And it WILL make things easier. But there are obviously much more cost effective ways to get to your end goal that won't hinder your experience. You certainly don't need the extra horsepower.
Dropping $1500 on a X99 platform you're just going to build it and then ask yourself... what the hell does this do that I couldn't do before? Aside from plugging more drives directly into the board.