upgraded both my 3/2 and 4/3 Xcel's last winter to the Infinity OS back zip from the $200 low end Xcel's. got both for $300 each with a little discount from the shop owner as we went to highschool together. the low ends aren't that good as the slick skin peals off the neck. The OS's ROCK! I'm too big & fat to contort myself into a front zip, but the OS provides a pretty damn mothrfuckin' good seal. like it's been said before the Xcel's material is PLENTY stretchy and softer than anything else on the market so the 4/3 is surprisingly not too restrictive in paddling. During the Jan07 So-Cal cold spell I was perfectly fine in the 4/3, except for my feet which I tried to not wear booties as any water in them throws off my feel. My only complaint with Xcel is their key pocket. On the OS it's placed really low on the back so after a winter dawn patrol session you get REALLY cold pulling off the suit all the way to your ass to reach the key.