I use one of those units (not branded "Turnigy", but identical) and I've not got any complaints. It outputs around 5.9V when the jumper's in 6V mode, which sometimes dips to around 5.8V when it's under heavy load. Runs cool though, and it's reliable too. The output/input wires could do with being a tad heavier gauge, but it's not caused any problems for me. Well worth the price if you don't need a higher-performance UBEC, IMO.
I've ran them on several cars, they work like they should, and are cheap. My only concern is, that I get more glitching with them than without. I have 4 or 5 of them. I have a bad rf problem around my house for some reason I havn't pinned down yet. It doesn't affect brushed cars, but pretty much all the brushless ones do it.
I have a few, and they work fine. They are a bit noisy, and I have had to move them around on the chassis to cure glitching. The ccbec is better, although it has its own issues if it fails (cooking receiver and servos).
Not bad for the price, and I have never had the turnigy fail on me...