I guess I'm against the grain on this one. I used a tru-peep last season, and it worked pretty much, but no matter how much I tinkered and twisted and fiddled with it, I would have to physically turn the string to be sure it would line up straight on draw. So this year I decided to go with the tube style and not have to worry about it. Yes there is a possibility of the tube breaking, but there was also the possibility of me forgetting to give the tru-peep a twist and not be able to look through it on full draw. I consider those equal risk. So to me the tube is more reliable because It takes ME out of the mistake equation.
IMO there's enough stuff to think about before and during a draw.