From my experience , the rotary ones are overdone and kill alternators due to it. Used to pull the old motor to 10k that would have the alternator doing in excess of 13k rpm / Water pump doing over 8k rpm.
When you look at sizing versus the standard pulleys can see how overcooked they are , New underdriven pulleys are v belt and will see alternator under 8k / WP maybe 5k prm at full noise.
Was cool for crusing around and nothing like that noise....Maybe trade again one day if i can find one of the old prototype 20mm sets.