We did 4x10 for a while at my office. I liked it and it supposedly saved a lot on energy bills not having to fire up the ac that one extra day. It was also nice having 3 day weekends every weekend for a while. I pretty much work 10 hour days anyways most of the time so the longer day wasn't bad to me but some other people in my office were complaining about being tired. I would say go for it and make sure your lights are charged up in case of a dark ride home.