I'm running mine this winter, and this winter only.
Have Toyo Snowproxies 215-45-17 on a set of Accord Type-S wheels.
No undercoating, will do a major cleaning this spring. I´m cleaning the car underneath atleast once a week aswell, no signs of any rust so far anywhere.
don't want any excess weight on the car for the summer so a undercoat will make the car much heavier then i want.