Go with the ghetto fabulous steel wheels when you put on your snow tires:
The MINI is just as capable as any other front wheel drive car in winter. If you, like me, live in a place where there are radio and tv commercials for snow tire brands, then you'll want to put snow tires on it. If the local service stations don't stock snow tires, you can probably get away with just all-season tires.
Drive sensibly, and you'll be fine.
And traction control / DSC is a good thing (ignore anyone who lies to you and says the owner's manual says to turn it off in the snow).