The ten inch is lighter. Do you recommend the ten or twelve inch saw? Why?

Add 25% to the biggest thing you intend to cut to arrive at the size of
the largest thing you will cut. I always go for a little overkill and
seldom regret the decision. There are some folding rolling stands that
make the heft and storage of the bigger unit a non-issue, for instance;
http://www.amazon.com/Trojan-MS-2000.../dp/B0000224RH
I'm not recommending that one, just an illustration, the price makes me
a little nervous about that one.