DiscreetCarry Clips. How good for beltless carry

[pgb205]

http://www.veilsolutions.com/products-page/quick-ship-items/discreet-carry-concepts-mod4-clip

One such clip can be seen in the link above. I would be curious to know any real world reports on how good these are for belt-less use? Jeans or nylon gym pants for example.

thanks