This is a very nice belt system. I used it all day, with my PDW, then switched out to my G36. No problem holding mags, but getting 3 M4 style mags in each pouch is a pretty tight fit, with high caps at least. The elastic retention for the mags keeps them nice and secure. I also put my Lancer Tactical M9 rubber bayonet, and a canteen pouch (with ALICE clips), and they fit securely. A trick to keep everything from moving around is to put one retention strap between the velcro on the belt, then your pouch won't move around. The 600 D material is lighter weight, so time will tell how well it holds up, but I think if you take care of it, and don't abuse the crap out of it, it should last a long time. The belt is nice and wide, and the buckle snaps securely. The inside of the pouches have some sort of PVC coating on them, presumably to keep the nylon from getting gouged by pointy corners on mags. For the price, you can't beat it, just for the sheer utilitarian purpose it serves, especially if you have a couple of different weapon platforms, as it will work for all of them.
Sturdy, thick belt
Decent quality buckle
Elastic straps hold mags very securely
Very versatile, can handle many different weapon platforms
Can mount other pouches/accessories on belt
Lighter weight 600D nylon
Pouches slide around a bit