I have the usual fibreglass style seats in the Ginetta. They were a little worse for wear and have been chopped about a bit.

Ideally I would like to paint them, but would be concerned about flex in the seat cracking the paint or clothing rubbing the it off. I don't really want to cover them in vinyl either...

If I painted on a gelcoat would it dry smooth?

Any ideas?

Prepared properly and finished with clear coat it will be plenty durable.

You don't want gelcoat in any case. That needs anaerobic conditions to cure. Flow coat perhaps...... The added styrene will allow it to set in the presence of oxygen.....

Polyurethane paint is very flexible and abrasion resistant.
Not cheap though...
(At least here in Mexico)