I'm using a Kraken G10 with an X31 AIO (two each) on my SLI 780Ti's. It's fantastic except the design of the G10 isn't optimal for VRM cooling. I installed copper heat sinks on the VRMs and it seems to be working ok. I would instantly buy a couple EVGA shrouds, but I don't need the cooler.
The other thing to be careful about is the tubing length. I've read here that the tubes are 14" on the AIO. On the NZXT they are 16". I have a NZXT Phantom 820 case, and it would be much more difficult with 14" tubing. I have the radiators mounted on the bottom of the case, side by side and it's a fantastic setup. The NZXT fans are also very quiet. I just don't get why we can't get longer tubing in AIO coolers. I suspect it's a cost saving issue since the coolers are intended for CPUs and the distance to the top of the case isn't an issue.
A request for EVGA. Thinking ahead, people who watercool their GPUs will have AIOs for a very long time. Don't force them to buy a new AIO when they get a new video card. Sell the shrouds so we can use the AIOs we have. Make them as generic as possible so they can fit a wide variety of GPUs.