I would second the above opinions that hinge-less frames will be best for you, particularly Birdy/Bike Friday. Bike Friday is custom made, so you can go for a stronger frame.

The Birdy can, without question, handle 110Kg off road/curb jumping. In my opinion, it is a bit over engineered for the average rider, with a 36 spoke 355 rear wheel. (You definitely don't have to worry about the wheel going out of true!) When they added full luggage capacity to the bike in 2002, they reinforced the frame to the tune of 1.5Kg of aluminum. I would like to see a model for petit folks (besides the Frog). Otherwise, little people are asked to lug around more bike than they need.

I think newer Swift models have been greatly reinforced, but there have been scattered reports of frame breakage on the older models. Never heard of problems with Downtubes, though the weld quality looks good but not outstanding.