Hi thor here
nothing about the other bikes in question
just a not about the Dahon snapping in half statement ...

All Dahons have 5 year warranty. All Dahons which get signed in the website or by mail from the owner have lifetime warranty.
The Owners signs in himself but it is expected from the owner that he had a dealer ( any dealer) do a Pre delivery check on the bike he is signing in.

Snapping frame ..I dont know about any one .... and I am pretty sure I would have heard about it :-)

Thor