I have carried IWB primarily now for many years and as a result have carried a great many holsters to find one that fits well, is comfortable and lasts for a long time. I have tried leather as well as kydex and with the extreme heat I have here in Phx I have settled for the kydex all year.
Look at the pic of my carry guns and the holsters and the one at the right is a "double loop" kydex made by Predator. It looks very similar to the double snap of the rig your talking about. Over all the years and rigs that I have tried this one has been absolutely the best and has lasted the longest and been absolutely the most comfortable for me of any that I have owned.
The attach unit of the one you show is actually quite long so it would have to be very flexible or it would seem to me to be prone to stretching your pants and perhaps not be too comfortable.
Mine is only 4.5" between the loops but it is very comfortable and does not stretch or in any way feel unusual.
One thing to consider when choosing ANY kydex is their return or guarantee as they will break in time exactly where you mentioned. Especially if they have to clip on type of loops or attach points over the belt. It seems to be the weakest link for this type holster so be sure they will replace it if it breaks.
Predator doesn't even question, they just give a new one. BUT I cannot find them now as since he left the Phoenix area for someplace in Idaho, I have lost track of them.
My point is that the holster I have looks very similar to the one on the site you gave with the attach equipment. Therefore it would seem that the one you are talking about may be equally as comfortable. If it will last or if they have a good guarantee, then I would try it. In fact I am thinking about trying one as I want a backup for my Predator.
If you get one, let us know how you like it and how it feels when you have hd it on for a while.