[venturaII]

Imperceptable difference in offset, so no effective difference in ride from that. You'll definitely notice the lighter wheels, though it's not a night-and-day change. Regarding the tires, I've had both Conti DW and V12 Evos, and I'd take the Contis (or the DW's replacement, the Extreme Contact Sport) in a heartbeat over the V12. Much better tire in every respect, IMHO.

205 versus 215 is a different issue. As mentioned, the tire category has far much more bearing on the tire's behavior than the size (at least, between the two sizes you're thinking of). Given that a 205/45 is going to be shorter than the OEM setup, you'll be changing more than just gearing - road compliance, comfort, sidewall flex, etc will also be different, and I'd assume that is a significant consideration where you live. However, you can change those just as easily with different brand/model tires, and still keep the factory gearing, and not have the additional empty fenderwell space you'll get with a 205/45.