I agree, though I have no experience. I do think barrett's a bit overpriced. There are a few other brands that seem reputable, or if nothing else way more "cool" since that's what half of the people buying one are after.
I forget the names, but there's one company makes a dedicated magazine fed both bolt and semi.

My favorite for looks is the RND 3000 (youtube it)
AR-50 like he said.

I really WISH oh so very badly we could get the GM6 lynx in the US.
http://youtu.be/ywh3OH8sHQM