Back in the days when I bought my own Victor Sprite 400, the speeds were as follows: Standard 230rpm, High Speed 400rpm. Super High Speed was then something completely different and it may well have been something like 1000rpm.
Today the ratings appear to be different. Standard speed is still 230rpm and I find it quite acceptable for carpet work as long as you don't use it to bonnet wool or "heel in" on synthetics, esp. polyprop. Todays Super High Speed would appear to be 390rpm and, IMO, not suitable for carpet work, regardless of pad or brush. I think they may now use the term Ultra High Speed for the zillion rpm machines.
Safe and happy cleaning

The Ken