I've never used those but I do know that the design of that does allow more error for slippage and thus could round off a bolt and not SAE bolts, like those found on bikes, are softer metal and will round off faster. You don't run into odd angles on bikes to even remotely worry about using those.

They are great for running bolts into waterbottle cages, oddly placed xtracycle bolts, oddly placed rack bolts and fender doodads.... then get in there with the tool at the proper angle for the last turns of tightening and the first turns of loosening.

I've never rounded anything off. (...knocking on wood)ar

People should indeed be well aware that they are more likely to round off a bolt. But the convenience is worth it. Try them sometime.

Ball end Allen's are great & and if I only could have one set then it would be ball end type. I always break bolt loose with other end first. I have about any type of Allen there is . I was an industrial mechanic

cheers

I have a few small Snap On tools 8,9,10 combo wrenches and a 1/4" drive screwdriver handle

with a magnetic 1/4" hex bit in it , to use the Phillips Bits that are hardened and cheap
for the drywall power screwdriver Builder's crowd..

My Craftsman 8mm hex bit pulled out of its holder almost every time I used it on a crank and was sometimes obnoxious with pedals.

My Snap On bit I bought for $11 used was entirely worth the price for the reduced hassle.

OTOH I never had problems with my other Craftsman hex and torx bits.

I ended up buying a Proto socket set for the large hex I will use with a torque wrench and for smaller Allen keys got Performance set with the ball-ends on the long side of the key. For the original question I was looking for large hex, (10mm) socketed, for which ball-ends don't exist.

The bottom line here is dont skimp on tools. Good quality tools can last a lifetime.

BTW I have a Sears socket set that my father had from the 30s.

Proto are great tools, probably equal to Snap On, or least they use to be not sure about the newer stuff. Also S&K is another great brand similar to Proto, again not sure about the newer stuff. Problem with those is if you don't have a local retailer any warranty issue is handled by mail which you pay for the mail. I have Proto and S&K and none have broken in over 35 years of automotive useage.

It is true that Craftsman back 30 and more years ago was decent stuff but today Craftsman is Chinese junk (just like all the home improvement store tools), you can get the same quality from Harbor Freight and pay less and have the same warranty.