I have a few different sizes of these and have found that they are realy to place when you need to move fast but they jam up a little too good when you slip and they catch your weight. there is an easy fix for that though. Brin a nut tool and a yosemite hammer and they will pop out. they wear out a little quicker than cams so keep up with inspecting them and routine maintenance and they make a super inexpensive tool for your arsenal.
I use these for basic single-pitch trad, and they work great. They place nicely in horizontals, and they work in really unique places. They are hard to regularly place though, because it seems hard to find the right constriction and size. They are also hard to get used to, since you really want to cam it in that sweet spot, which seems hard to find sometimes. I wouldn't want to fall on the smaller two, personally, but the others are pretty incredible.
"Extremely useful, especially for runout pitches with sparse protection and sketchy thin placements.."
Bought a set of these to back up my small sized cams and havn't regretted it for a minute. On scary runouts where gear placements can be tricky to find or the cracks are simply too thin for a cam, ballnuts are saviors. Very easy to use, and even easy to remove when placed correctly (and not fallen on) these are extremely handy when the cracks simply get too small for a cam.
These are a valuable addition to any rack. These little guys are ideal for aid climbing but they are even more useful in a sketchy situation when you don't have time to fumble around with your nuts. Throw one of these bad boys in and carry on your merry way. These have saved my skin on many occasion.
Make no mistake - these little guys will hold a tremendous amount of force in otherwise unprotectable tiny cracks. They're awesome in that regard. The down side? They're damn near impossible to remove once weighted. I picked up the two smallest sizes and used them with good results free climbing. I took them aid climbing, though, and both became fixed gear on their first placements. They really wedge themselves in good under even a body weight load, so don't expect to get them back once you've weighted them. I couldn't even rip it out with a funkness device (so they're definitely bomber).
If you have already used these awesome tools, then you know how great they work. If not, check them out. A little spendy, but what price is too much for piece of mind while climbing? Buy some, use them and climb like a rock star.
These are an awesome design! Thanks Jeff Lowe. The cable is nice and large so there's no worries slotting one of these and doing a bounce test. The range is great for climbers like me who haven't got it dialed and have to fiddle around with a few different sizes. The only negative is the price but how much do you think it's worth when you have to hang your butt out on it?