Tom,
I use 1 1/2" gaffs on poles without bark and I have climbed a few trees with them but anything with rough bark is a real gamble.
Tree spur gaffs start at 1 3/4" and go up to 3 1/2".
With no bark you come straight to the bottom if you cut out unless you get real lucky and cut back in on the way down then hope it`s the pole you cut into and not your leg.
Your arms turn a nice fleshy red color on the inside and you have mega slivers for a few months.
If the pole has had a creasote treatment it hurts even more.
With really rough bark and a rope lanyard there`s a pretty good chance you`ll get hung up on the way down.
For laughs when working on the opposite side of the pole from another lineman we`d slip a gloved hand in the form of a fist between the linemans belt and the pole as he was strapping in.
Just when he leaned back and wiggled his butt to get comfy you pull your hand out from under his belt and watch his eyes bug out.

We were much younger then!