I am not so sure about Brown Bead (I have heard nothing but good things about it, I think someone told me that its adhesive isnt the best) but I can tell you that the edead v.2 is awsome, I got myself some and am extremely happy with it. you can look at it here :
I recently bought 35 feet of brown bread and i must say it does the job. Ive never had dynamat to compare it to but the only rattles i have now are in behind my lights where i cant put the mat down. I just bought a can of spray stuff to fill in those areas and the cracks.
well you could do the easy thing and use a tape measure to rough it. You always want to buy a little more than you need, to fill in the cracks and all.