a guy at work has a Redi-Mag. He seems to like it, but i don't like the fact that when you hit the mag release the mag in the Redi-Mag falls out to. He says with practice it won't happen. I use a Molle 6 mag carrier that I can just throw over my head when I leave the squad car, if I take the AR. My first mag has the $5 mag coupler, though. It is still alittle new and i'm not sure if i like it. It is a fast reload, doesn't really throw off balance (that much), and if a do a tactical reload, the partially empty mag is still accessible .
One drawback is it doesn't fit in my little Molle pouch...so i don't know what to do with when I reload again. I think I need to get a load bearing vest that says POLICE on it. that would probably be better.
anyway...try to evaluate what you'll use the ar for. in my case it is a patrol carbine to be used for SHTF stuff, like in a school or Johnny Jihad type stuff. Once you find yout what you need it for reload options will become mor clear.