I've got one. Used it at the Red for a 4 days of climbing in May 2006. It works very smoothly--I think a safe brake hand position is a bit easier with this than the grigri.

The only 'gotcha' I found is that when held at a certain angle it won't feed rope, no matter what! But simply pushing the entire device down a bit allows you to feed slack as smoothly as with any device out there, including non-autolockers.

We used it with my Beall FLyer 10.1 and also a PMI 10.2. Both ropes fed smoothly through the Sum, and lowering was a bit more controllable on my Beall than with the grigri--that rope seems to fly through the grigri for some reason. I'm much more confident using this device with thin ropes.

If you've got a grigri there's no reason to get one. But if you're looking for a good device for skinny ropes, I'd get this over the grigri.

The weight of the Sum is 260 grams. A Grigri is 225 grams.

I have the lace-up Magnet and HOLY COW! IT' SO GODDAMN COMFORTABLE! I'm giving them an enthusiastic 5 of 5 for sport climbing. The fit and comfort are so good, they can't help but be excellent performers. You've got to live up to these sharp looking tires...I haven't crack climbed in them, but I've done some agressive heel hooks and heel-toe cams--they really made me levitate to the point that I have a slight hamstring pull. I hit the steep pockets at the Red, the horizontals and roofs at the Meadow, and some edgy 5.11's at Endless.

It is extremely precise, 5 of 5 for edging, exceptionally easy to use on the smallest edges and points. The rand is very thin--this means you get great feedback on your foot positin against the wall.

Smear performance is 4/5 because the rubber is very thick--I don't think the shoe conforms well to small rugosities on large smears. Laterally it isn't exactly stiff, but it isn't soft, either. Probably a bit softer than the Muira, but I'm open to debate on that. My expectation is that with a resole and thinner rubber, they will break in and become even more sensitive and softer, able to smear more effectively.

I've got the previous Annihilator. It's fine, not as durable as a Hilti but then nothing is you know.

Kind of strange the way Reardon talks about the hammer motion as if it is something he's just discovered. You'd have to be an idiot to use only a simple rotary drill, and battery powered hammer drills and rotary hammers have been around for 20 years.

I'm not familiar with SDS Plus, is the chuck redesigned? Do SDS bits work in an SDS Plus tool?

Update:

I've now used this for many weekends of sport climbing at the New. Remember, it won't work at all with wire gates biners. It works fine with Petzl Spirit biners. Practice makes perfect.

I've found the hardest part is getting it to release the biner after clipping through the hanger eye. Seems to work if you push up to close the gate, then twist out.

The whole apparatus is cheap feeling plastic. I'm pretty sure crucial parts will break before I've gotten my moneys worth.

Clipping the rope through a hanging draw is still a bit difficult. With my Mammut 10mm the rope won't stay clamped-maybe this thing only really works with big fat ropes?

Removing a hanging draw is useful, despite petsfeds, comments. Maybe he's never had to clean a very overhung route, where if you lower enough to clean bolt #1, you are looking at a pendulum into the ground....

UB