Since it has a top that is relatively easy to put on and take off, plus has a great storage method (unlike Ferraris where you have to put them behind the seats), it should be just as easy to live with (I own a roadster). They only downside might be less chassis rigidity, but that hasn't been an issue for anyone I know. For those who love open air driving, the Roadster is just nirvana.
Can't help you with RHD values....you might want to go look at the pistonhead forums.