The ring, IMO, indexes the blade in the palm of your hand like the bumps on the <F> and <J> keys on the keyboard. You know the position of the khuk in your palm without having to look. So for that reason it is very functional.
That said, some of my khuks have had rings that just don't work with my hands. Bye bye ring.
Some of my khuks the handle has been just too big (most of them), so I reprofiled them. Where possible I keep the ring.
Modding these knives is really fun and rewarding, and really requires very little in tool expense. I've refinished (at the least) every one of my khuk handles. The 'polish it with rouge' method of finishing wood hides the figure something fierce. If you refinish your handle it'll look better than ever.
Tape off the bolster real good. Sand the handle down (use files if you're changing the profile). If you intend to keep the ring, protect it with superglue once the original finish has been removed. If not then just go nuts on it. Sand to 220. Switch to scotchbrite (maroon, green, grey, white). Apply Danish oil. Gorgeous handle every time, and really I can do one in an hour easily.
My point is, if the ring is impeding function, remove that bad boy. The M43 doesn't even come with one, and is a very nice khuk.