I like the design, look, and feel of them. I believe metal reinforced polymer is a better design than pure polymer. I like translucent. It is easier to check the mags than the window in a pmag. They also fall free in rifles that some pmag gens don't fall freely from. This makes me sound like I don't like pmags. Not true, I love them and use them. I have been using Lancers 20's at the range though and I haven't found anything not to like. I would like to get some of their 30's to try out.
I think you can buy them with confidence.