yeah the GPU client is very nice. I do cpu/gpu clients, I just started back doing folding after a long break about 2 weeks ago. I do have to say yea it might use alittle extra power but its not like you have to leave it on all day/night or at 100% cpu usage, i set my cpu to use about 90% and I do leave it running when im sleeping, I don't like powering down my rig unless its to upgrade or to clean the fans out. It's for a good cause so its worth a few extra bucks a year for electric. Normally the cpu client is always on if im playing a 3d game I pause the gpu client till im done. I don't care about winning prizes for folding. I look at it this way, it will either help me when I get older or help someone in the future. I do understand though that you dont wanna waste your money for something that you see as frivolous. But to those that do still fold or the ones that will in the future give yourself a hand. If anyone needs help or whatever with folding let me know.
It's not all about the prizes. They only gave them away because AMD, Palit, and ECS realized what kind of impact they were making in contributing many hours of work therefore donating hardware to be put to the cause.
I still Fold, but use an old system (Socket 754 3200+ & ECS board) dedicated to that purpose. It runs 24/7, it's not fast, and I don't belong to a team or compete for prizes. Contributing to the effort is more than enough for me. The cost of electricity to run the program won't make or break my life.
I have F@H installed on another computer and run it in the background (CPU-O/S usage ~50%) while I do other things, but it gets shutoff @ night.