I drive deerfoot every day, and budget to replace the windshield every spring. Part of living here.
As for the settings. My winter setup is quite compliant especaialy with the 17" winter wheels. Understeer is more predictable on slippery roads and although you feel more it is far from uncomfortable. Put the summers back on and just the change to the lower profile 18" firms it up enough to rail it through the on and off ramps. I hope one day to drive on a track where I can really firm them up but have a feeling the tires will be the limiting factor.