As for the fear of wrecking thats a silly argument if I'm being honest. You got the car because its a blast to drive, so go and drive it, enjoy it. Stuff happens, its out of your hands! 335is is a great all around car but it doesn't excite on nearly the same level. I won't give up driving pleasure for a sunroof.. and I really love a good sun roof
Don't be afraid to drive it because its limited production or insurance complications... the car is
FULLY capable of handling well in wet weather and with proper tires even moderate snow. The only reason to not drive it would be if it was not capable of handling such conditions. Cars like the ZR1 on cold tires in winter for example is a problem waiting to happen... the 1M is not, not at all. As for salt on the roads you won't damage the paint finish, modern BMW clearcoats are very resilient. Keep it well waxed and wash it regularly , blast the undercarriage with a pressure washer and just drive the thing.
Why don't you drive your X6 more and save 1M for better weather, road conditions..