If you enjoy driving, the R-Design is a different car than the regular C30. Great power (225hp), tight steering, firm suspension, quality can be felt and wind noise is almost nonexistent. I would recommend this car for the enthusiast but it's not a convenient family car because rear seat access is not something you want to deal with regularly. Rear tires wear quickly but if your alignment shop is really good, rear settings can be altered slightly to help with that. Factory brake pads are good but dust the rear wheels heavily and I am happier with EBC Red pads on back and will probably go to them on front also. Water in floor (frt or rear) could be sunroof drains in A pillars (short tube or plugged @ firewall) search youtube or Volvo forums.
I bought C30 four and half years ago used with 20K. The handsome external design expresses my style well. It is practical (overall small size, with easy back seat conversion to increased cargo volume), well balance (power and mileage), and simple inside. I used it to transport tools and materials for home improvement, to take my dog to the park, to go skiing (roof ski rack), and to go on hikes from trail heads far into the Washington state Cascade mountain roads. This car does all of this at good mileage, reliable services, and sporty feel. At 85K, so far I had no unscheduled repairs. If you want luxury handling and interior noise level, with plenty of power for passing and roadstering, at small fuel mileage penalty, get it!
After years of driving Volvo sedans I looked for something sportier in the Volvo family in my price range. I chose the C30 T5, the C70 coupe was my next choice. It came with 18" wheels and low miles and was in good shape. The sacrifice is size and storage. But for a daily commuter and the occasional road trip it is perfect if you don't need a lot of space. From my research on maintenance it is relatively inexpensive compared to higher end hatch coupes. The interior finish is pretty basic but ergonomically it is very comfortable. It's kind of low so getting in and out took some getting used to. Overall, I like the unique styling, handling and value for a car in this category.