Well, snow and general cold. The AC has a leak (another notch in my list of things to do), so when I was using it this summer I left the back window open. I didn't think I was doing anything particularly dusty. Boy, was I wrong. Saw all the dust collected around the cab and gained some appreciation for the added value. Then you throw in the rainy summer we had (pretty nice when it can't really decide to rain or not). And it is less noisy.
And perhaps equal to having a heater -- with the lights and the mounting locations (front and rear -- bigger alternator with a cab) I can extend my working opportunities. You do need ac with a cab though, it's a big greenhouse in the sun (not just a luxury). A friend said it was 'decadent'.
By the way, nice by-line!