I bought a set of time trial rings awhile back, (May) on the advice of a friend. I also did some research and found some good write ups on various cycling sites.
I also came across a place that had the rings on sale so i decided to get a set for my road bike. The TT rings are 54-42 and the road bike is compact so I ordered 52-36 for it. The installation was easy, they provide good instructions. They also recommend riding 300 miles or so in position 3 to get used to them, then move them to a position that works for your riding style. I skipped that and went to the masher (less cadence) position (4) from the start.
I've used them all season and i do feel they have helped me get a little more power to the road and i haven't felt any unusual knee or leg pain. Haven't used them on any long steep climbs yet, we'll see how they do next spring at the SI training camp.