I hate to continue tracking this thread off topic, but what's with the discrimination against non-av'd members? Everyone seems to think that because you don't have a little emblem under your username, you don't deserve respect and/or help. I understand the concept of refusing to help these members get their hands on particular things, but you guys seriously need to lighten up. Some of us aren't able to get av'd, due to the trouble that comes from the whole ordeal, and others just aren't 18 yet. I think it' ridiculous to just assume that a 25 year old is more mature than a 17 year old because of a few years difference. I very well know of 15 year olds more mature than people of age, and I wouldn't hesitate to have a skirmish with them. I just don't understand the assumption that someone has to be 18 to be mature. Seriously, get over yourselves.
Now to get somewhat back on topic, the choice between the two is somewhat simple if what you really want is full metal. As everyone else seems to be suggesting, it's much simpler and cheaper to replace a rail system than a receiver.