The guys at Gebhardt treated me well. They weren't my "local" dealer but they were willing to deal with me over email rather than making me come in; a hard thing to do when you have kids.
Regarding the 19" wheel concern in winter weather driving conditions, I wasn't concerned until now. Why would there be a difference between 18" and 19"? I didn't explicitly order it with the 19s but as it was already on its way I went ahead and paid the extra $$ rather than wait for a custom build. They do look nice! I'm currently working with my dealer to get the all-season tires on it. The build sheet said it was supposed to come with all-seasons.
2013 BMW 335i xDrive Sedan, Mineral Grey Metallic, 19" Light Alloy Double-spoke Style Wheels