As for the Nismo wheels, for my personal opinion, there are a lot nicer 19" wheels out there for less money. I wouldn't go for them, but depends if you really like them or want the Nismo badge.
As for the roadster question, I'd have one as I love to drive with the top down. If you are one of these people that have a cab and keeps the roof up when the weather is anything less than 90 degrees and on a quiet road etc, then don't buy one.
Winds me up with roadster drivers (in all makes) that don't have the bloody roof down. When I had my S2, had it down everyday that it wasn't raining, or if you doing a long motorway journey etc....
But personal prefs, just take it for a decent run and see.......