OrangeGuy I think you hit the nail on the head. At one time I was also thinking about a cab for my TC-40D but then if I had added a cab for winter use without AC it most likely would have been like an oven in the summer months with the added solar load. I really don't want to add a cab for winter use and then take it off for summer use (I'm too lazy). Besides I'm a fresh air freak and a bit claustrophobic to boot.
Now if I was working in a very dusty or dirty environment, or if I had an allergy to cut grass, ragweed, or the like then I could justify a cabbed tractor with AC and would be content with the added confinement.
I don't see it in the cards for me.........