I'm torn between the two. Both portable and cost the same. I like the MB1215 speaker configuration, but is gonna be loud enough for ''most'' situations? But I like the expandability of the RB510 for later on down the road. I'm playing straight forward Rockabilly with an M1, Super Silver strings and a k&k RAB pickup. ...small to med gigs... $600 is a nice price tag and is right about where my budget ends. http://www.carvinguitars.com/products/MB1215 http://www.carvinguitars.com/products/BR510 thanx. and I'm all for other suggestions in that price range.