I briefly owned a B5M, then just switched to Serpent MM over the past week. I'm not a pro driver, just a regular guy who enjoys club racing at the local track. In my opinion so far, the Serpent definitely allows me to drive faster. It is a well designed car and I think it is a better choice in terms of quality and design over the B5M. BUT...the B5M will have the best parts support and more guys run Associated, period. If I was in your position, I would look at two things: parts availability and what cars are popular at your track. Serpent is getting fairly popular around here in SoCal, and more places are starting to stock parts, including amain, which is why I chose Serpent. If you live in an area where everyone is running AE and you would be the only guy with a Serpent, go B5M. It helps to have support of local drivers who have the same car and local shops that sell parts. Just my two cents.