My V2 came in today and from the pics, the fan is identical. The base and heat pipes of both coolers are the same. The only differences are in the fins. The V2 has larger fins and has little dimples in it (to catch air?). The back looks closed on the xigmatek, but it might just be the pics. That might account for the slightly better temps, but at these prices, it's a toss up imo. Time to install it all.
Note on these coolers: According to a guide I read recently, they got the best performance by lapping the bottom and then filling in the groves in between the heatpipes with thermal grease and then applying a normal amount to cover the cpu. I don't plan on lapping mines yet, but I'll follow the other instructions.