Flows are great bindings for big people. This is because bigger fellas like yourself have a tougher time strapping into traditional bindings. Flows take care of that because of their quick entry. But as everyone stated, it takes some trial runs and adjusting to get them just right. That is unless you get the SE versions. The SE versions mix traditional ladder system with Flow's. The inner straps have holes that you screw the cap into. Then you simply crank the outer ladders down on your boot like normal bindings and you're pretty much set to go. This system also gets rid of the notorious powder problem with Flows of yesteryear. You can actually treat any newer Flows this way anyway because of their mini-ratchet system.
The biggest benefit of Flows however is the comfort. Flow's caps have a even pressure distribution on your feet causing much less fatigue. There is a cost though, you don't get as much response as traditional bindings. However, the difference is highly negligible. I can still do everything on my Flows that I can on a traditional binding.
NXT-AT is not the binding to get. It is a great binding, but there is one better. The NXT-FSE. It is basically a lighter version of the AT or ATSE. I have demoed all of the SE Flow bindings for 2011. The NXT-ATSE is great. However, if the cost difference wasn't an issue to me, I'd go with the NXT-FSE. In fact, I do own the FSE and I chose that over the ATSE. You can get the regular AT, but I recommend the SE version.
As for your board, magnatraction will be great for East Coast riding. It absolutely works on ice. With your size 13 feet, you do need a wide board hands down.
BTW: The SE versions are lighter. The NXT-FSE is really light. I love them! I don't know what your friends are talking about or what Flows they have tried, but they aren't as heavy as they once were.
If you want the 2011 ones:
We don't have the 2010 models in your size