Seems like a great idea until you think about it and/or try it. 2 matters.
First and foremost, the trigger should be covered when carrying. At the agency there was a negligent discharge (no such thing as "accidental") using a Versacarry carrying device - it's NOT a holster. The person had fallen in the parking lot dislodging the PF-9, with Versacarry still attached, from his belt (crossdraw carry.) He was bending over when it fired due to bunched clothing. He (and everyone in the area) was very lucky - a pair of pants were singed and split at the seam. Remarkably, no disciplinary action.
Second, be careful in use. For the P3AT, switching hands will cut you - shooting a P3AT left handed with the right-handed clip or vice versa will cut you. This is not necessarily the case with the PF-9. I can personally attest to this (and the wisdom of having a first aid kit in your range bag.
However, there are some motorcycle patrolmen who like to carry some "insurance" inside their high-topped leather riding boots on the inseam side. While they understand the safety issues, they are confident in their handling. We wish them good luck.
Bottom line: The clips can provide a handy way to store a pistol in an out-of-the-way place, for example, under a shelf. But for EDC, covering the trigger is far more important than the slight improvement in concealment - today's IWB holsters are plenty concealable and, for me, they are much faster on the draw than the belt clips. YMMV.