Faders SUM Review

In conclusion, the SUM is pretty much a Grigri clone -- it handles any single-line technique just as well as its papa device. If you prefer thick ropes, I'd stick with the Grigri. On the other hand, if you're one of the new breed of sport climbers working long, difficult routes, where the weight of your redpoint cord really matters, the SUM, which should hit U.S. retail shelves this fall, is your tool.
The SUM ranks lower than the Grigri 2 simply because it isn't as smooth to operate, although with practice it does work nearly as well.