I'm a big fan of the S&W pistols and have been looking at an AR for a while. I hate not knowing anything about a product, so I've been trying to do research before any purchase. Is there anything on the other models that you can't add to the Sport? There's over a $300 price delta from the Sport to the next model and being my first AR purchase, that's a lot of cash. My thoughts are to get the Sport as an intro and see from there what else I'd want or need. However, if there is something the Sport can't do or upgrade, I'd hate to spend the $600 and then find out.

Also, Bud's has an Adams Arms blemished rifle for a little more than the Sport at $629 AA 16 Carbine. I can't find any information on these, but the reviews on Buds are all great.

Should I stick with the Sport, go with the Adams Arms, or save more cash for another M&P?