There was a thread in TBN somewhere about people putting metal screws into motorcycle tires and racing with them. I read this and decided to put screws into the outer part of the lugs of the R1 tires on my Gravely. Didn't really have a chance to test them out because I got my JD not long after that and used it to plow my driveway almost exclusively after that.
If you don't have some steep parts to plow and have 4wd, you likely won't need to stud your tires or to have chains. However, if you ever really have to go on ice, chains or studs would be the way to go. We once vacationed in Hokkaido, Japan. They didn't seem to clear either the sidewalks nor the streets there. All the cars had 4 wheel studded tires. They ran around on the streets fine. Of course, none of the people had studs on their shoes, and they walked around on the ice fine while the rest of us were falling on our butts.
After the initial effort of putting the screws into the lugs, they're certainly the easiest way to allow for icey conditions. Chains are a pain to put on. Always hated them. Used them once on my car in NJ and once to push the snow blower on my Gravely here in Va. Hung them up on the brake backer plate on the Gravely and broke a link. Thought they were about to rip the tire off when it happened.
Ralph