The biggest difference the 710-712 CB is the finish.  The new satin finish makes the club look a little smaller and had a lot less glare in sunny conditions.  the Perimeter Weight of the cavity is significant compared to the MB and the CB's have at least a 30&% thicker sole compared to the MB.  If you like picking the ball off of the ground you'll love the MB with the trailing edge relief but if you make big divots and try to really compress the ball the sole of the CB will be more beneficial.  I personally have a mixed set.  (4-6 CB and 7-P MB)  I really like the make up personally.

Thanks for the info  I dont make huge divots so are the cb's not right for me