I've used the clipdraw quite a bit (know the folks that make them...so). I like it, but agree that it isn't a replacement for a holster. The good news is that most holsters are cut in such a way as to allow the clipdraw to remain on the gun.
Problems? The weapon shifts regardless of how tight the belt is. This is just the physics of the design and nothing can help it.
That's about it. It is a great little add-on but there are drawbacks. Get one and you won't be sorry. Just don't expect it to be that miracle cure.
P.S. while your there, get yourself a Woodsman's Pal. This is the greatest machete/bushax to ever come down the pike. If you have brush needing cleared, poles needing cut....whatever....you'll like how the Pal performs. Excellent balance, great edge-retention. Fantastic stuff.
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When Reason Fails.....