You have to take those manufacturer ratings with a grain of salt. People over at candlepowerforums have done some real world discharge tests
on a bunch of the 18650 batts out there. It's interesting and very enlightening.
Yea, the lithium polymer batteries are amazing, hard to find them in a cylindrical package though. They're mostly flat. I'm looking at doing a box mod with a lipol batt
that's 74x64x9mm (about the size of a cigarette pack, but much thinner) and it has a jaw dropping 5ah. It's a real world rating at .2C down to 2.75V so it's no exaggeration. Comes from a battery company based in Silicon Valley and it's pretty cheap, considering.