I've brewed with a Zap-Zap setup for my last 5 or 6 batches. (Note: I thought it was Zap-Zap but Zap-Pap makes MUCH more sense!) I've gotten decent efficiency with it (75-80%) but as Got Trub pointed out, it is a serious PITA! It sucks to clean (imagine rinsing out a bucket with a thousand holes in the bottom...) and after your sparge, you've gotta keep the two buckets together until you transport your grain to wherever you dump it (unless you want little droplets of wort all over the garage/kitchen/etc.). In my case I had a spare bucket lying around so it made the transition from extract to AG really easy, but I'm already looking into a cooler system. In other words, if you've got the spare equipment, play around and give it a shot. But if you're in the market for buying something new, don't waste your time.
Didn't realize how old this post was, my bad...