[TGHI]

I've not needed hub centering rings before, are there any big disadvantage to them?

Nope. I've been using 'em forever.

If you live in a place where rust is a thing, you might want to take a little care to make sure the surface where the rings sit is clean before putting them on, and when taking the wheels off to make sure the rings actually come off of the hub (otherwise you'll be trying to cram your regular wheels over the ring).

Also, go for metal rings since plastic/nylon rings can get deformed and pinch on themselves. The cost is negligible and will save you headaches in the long run.