I like the idea of a horizontal mag pouch as it could be more comfortable and easier to conceal. I've seen people wear them strong side (right handed) at 1-2 o'clock, but that seems like an unnatural reach and could be hard to get to laying down or kneeling. And forget about it in a car with your seat belt on. I'm thinking 7-8 o'clock for a righty might be a better choice. It would allow grabbing the mag from all postions and possible even belted in a car seat. If there is one with an adjustable cant or just slightly off horizontal might make the removal even easier.
Thoughts? Anyone have anything like this?