It also depends on the class of car. . .
With 1/12th or Pro10 the larger speed controls just weigh too much and have an actual impact on the car's performance. Yeah, it's only a half oz or so, but it still makes a difference when you're trying to cut weight.
For stock sedan, the 7.1 is better - has more punch, more capacity, etc.
FWIW, though, I haven't seen all that many problems with the Quantum Comp - and those numbers seem low. . .oh well. I mean, you have to tape the thing to keep it together since it's only snapped together. . .but once you do that, it's been trouble free for me. . .for more than a year