I've been reluctant to bring this up so as not to freak out all the convertible owners, but this might make an interesting experiment.
My brother in-law ownes an auto upholstery shop (for 20+ years) that just happens to do convertible top repair work for a local Ford dealer. He has had three convertibles in for warranty work and all three had the side arm, the one from the back to the middle, twisted.
His opinion is that it seems the metal is way too soft, like it has not been heat treated. Apparently the bar gets in a bind when the top is on it's way up and twists the crap out of itself, somtimes tearing the one piece top in the process. What made it get into a bind? Maybe someone sat on it or tried to put up the top with the boot on. Maybe it was a flawed top from the start.
Now here is the kicker, all three cars are owned by Hertz, so he couldn't get any feedback from the operator. Ford has been paying to fix them all, so far.
What are the people renting these cars from Hertz doing with these cars? Driving them in parades maybe? Who knows.
While he did say that this is the best top Ford has ever put on a Mustang (he compared it to a european top and definitely from a new supplier) he would not reccomend anyone buying a convertible for a year or two, until Ford worked out the problems. Thing is, if not enough of them break under warranty, Ford will not see it as a problem.
Anyhow, I say go for it and let us know how it went. I have personally seen an 05 GT vert in a parade and everyone was wearing smiles, including me.
If it were mine? man, I don't know. You gotta bite the bullit sometime, it might as well be under warranty.