[Super LX]

I'm looking at two kits: Factory Five and AC.
FF provides a lot of info. on their car but, there is less info. available for AC's car. I like what Roscoe and EddyTheB has done with this kit. I really like the simplicity of th AC car. I would appreciate any help answering some questions I have.

Does the roll bar provide protection or is it for looks?
I have seen some post where the fiberglass is cracking, is this a problem with the bodies or installation?
What is the advantage of kevlar?
How well does this car handle/perform and why don't most roadster kits come with anti-roll bars?
How well do these cars hold up to a lot of miles?

Thanks,
Cliff