Just as likely as it would be with any bow. I usually can't my bows and I was doing such when both broke, both in the handle so the wrap slowed it down some.
I haven't had one fold but I've had one just take a good bit of set so I reprofiled it and it was allright.
Mine were around 10-15lbs above average but I think just adding a few extra inches to distribute the stress better (like you would with a wood bow) would contribute to the safety and longevity of the bow. If you flatten your bow sufficiently and don't burn it, there's no reason to worry any more than with any other bow.
I also barely weigh 150 so I find it helpfull to have another person to stand on the jig to form the bow to ensure considerable flattness.
Also, if you are worried about the fumes, I am
mostly sure that you only get the worst harmfull fumes when you burn the pvc (which ruins the bow anyway), just lightly melting it doesn't produce nearly as much, if any.