I've actually used a number of them, both vests with internal carry and as a means of concealing an IWB AND OWB holsters. The Kakadu vest and another one (sorry, can't remember who made it... I'll try to find out and post) were the only ones I've looked for internal carry. The 5.11 vest, and similar others, were made of too light of a material to carry anything larger than a subcompact polymer-framed 9mm or smaller without noticeable sagging so I normally used them as cover for IWB or OWB carry and as sort of wearable SHTF bags. The Kakadu vest and the oilskin vest were fantastic for "internal" carry but, unfortunately, they have some problems of their own. The Kakadu's upper pockets are practically useless and I'm not too thrilled by the durability of the sown-in elastic holsters. I wore out the holster in my first vest just practicing and getting used to the draw. The oilclothe vest is holding up really well but has almost no pockets compared to the others. Every single vest I've tried has had major disadvantage one way or the other and I've personally given up using them for anything more than for concealing an IWB or OWB holsters. THAT they do very well and the added "cargo capacity" pretty much sticking to the 5.11-style "cargo" vests
