i would have to look into the convertable thing.
For one thing i don't think convertables are lighter because they need extra bracing, so really i think they are going to be maybe 200lbs heavier than stock?
Will the sanctioning body (i'm assuming SCCA) allow you to run the top down? If not, i'm thinking a regular hard top would be safer AND there maybe extra additions required in order for the convertible to be legal to run (again not sure---i would have to check the rulebook which is online.)
Yes, the maro is heavier but man they handle magnificent.
Can i ask where you live?