First off, EDCgear's version is no good. It's too stiff and difficult to clip on and off. Its advantage is it has holes on both sides, so you can clip it either way. Also, its holes are bigger so you can attach bigger split rings to it. And since it's so stiff, you don't have to worry about deforming it (it's just really hard to use).
The P-7 knockoff looks exactly like the real thing. You can distinguish it from the EDCgear by its brushed surface, while the EDCgear one has a shiny surface. This one works pretty well.
Both have some spring, but they feel like they'll deform if you bend them too much. I feel flexibility is a key requirement of such pocket clips, yet I haven't seen a single one with good spring. The P-7 claims to be made of spring steel. Conclusion: there are some differences in the real P-7, but I haven't found justification for the price, especially since it's not very springy.
DIY alternatives: I thought of using a cap from a nice pen.
Commercial alternatives: although the P-7 seems expensive, it's actually one of the cheapest (branded) clips out there. See the Scout hook and GambleMade Mini-D, both Kickstarter projects. None of these appear to have any spring. Looks like proper springiness is hard to design/manufacture, but without it, how do these justify their prices?
Update 18 May 2015
After using it for a while, I can say the original P-7 has a nice finish (probably bead-blasted) with smoothed edges and feels solid in the hand, so it's slightly better than the knockoff. However, it also lacks proper spring:
Summary of clips without spring:
- TTpockeTTools TT-Capper - none whatsoever
- P-7 - very little
- Scout Hook
- GambleMade's - I have their spring tempered bronze VolksDangler, and it doesn't have appreciable spring either. It even came with a gap so it already can't clip onto thin pants.
- Munroe's - at least the EDCgear version has, I'm not sure about the original
- Cogent HangKey 2
Clips to test: ?
This is just ridiculous. People are paying way too much for products with poor designs that don't even work. A good dangler will be able to hang on to a single sheet of paper, and not deform after clipping onto a belt - this is a common and reasonable use. And it's not too difficult - the EDCgear Munroe dangler can do this for ten bucks. These makers should work on getting their basic functionality right before adding all the bells and whistles.
Update: The HangKey 2 has amazing spring! I can even clip it onto my finger without deforming it permanently! Only problem is the gap is still a bit wide; it doesn't grip onto thin shorts. So still not perfect. Remember a clothes peg can do all this.