I'm buying rims for my soma frame. Aside from price, I'm not really sure what the practical differences between these two rims might be. MA3s are less expensive, and my sense is a little heavier and a little more durable. I might go with open pros for lighter weight, but not at the expense of durability. I'm planning on lacing 32 3x on both with 14/15 double butted spokes, and probably running 25s at first. I weigh 190, and ride pretty rough roads with little regard for potholes, and curbs. My sense is eitherither rim would probably hold up, but I'm interested in hearing people's thoughts on the pros and cons of one or the other.