I own a Guide Mesh Vest, and love it. I've had it for about 3 years, I guess, and it has held up very well. It's a little lighter than the regular vest, obviously, but holds everything I need it to, and I still have empty pockets. I guess it can get heavy at times, but that's usually because I'm carrying around way more stuff than I actually need. In my opinion, the best part about it is that since it's mostly mesh, it dries really fast, in the event I wade in a little too deep, which happens more often than not.
I suppose it's cooler in the summer, too, but I haven't really noticed a difference between it, and my previous vest.

B