I run esstac mag pouches on my primary belt (rifle and pistol) and my USPSA/IDPA belt but the GBRS pouches have me very intrigued. Does anyone have any input on these? I am not finding a lot of reviews/feedback on them. Thanks!

Is this pouch going to do anything better than what you currently have? It just looks like a ten speed clone.

which part is intriguing about them?  I'm not saying this to be a dick, just to be objective.  
There are lots of good elastic based pouches on the market, and quite a few that offer the ability to add flaps or bungee retention.  I personally use velcro one-wrap to attach my pouches so the GBRS ones are out for me.  
The Shaw concepts elastic pouches have been good to me for the last few years.