I have never been a fan of the Three-way Allen or Torx wrenches even though I own them. As was said before, they seem to be fine to tighten new bikes and bolts but after that I find their tolerances to loose to use regularly. My go-to Allen wrenches are PB Swiss with Bundhus coming in a close second. I have never stripped out an Allen bolt with those and I also us their Allen and Torx bits in my torque wrenches.

Then there's the always awkward (to me) feeling of the three-way wrench. I never got used to using them and they don't fit in a pocket very well but to tighten a new bolt they are adequate but I use a torque wrench to get the bolt to spec.

For shop use though, they would be very convenient because you have the sizes you use 90% of the time in your hand. Those things came out after I stopped working in bike shops though. That may be the biggest reason I don't favor them.