I'm afraid the RC31 doesn't have 20mm travel.
If you look at the PACE website, what it is saying is that the length (419mm) is the equivalent of a 65mm suspension fork (their new 439mm holloform RC38 race) set up with 20mm of sag.
It does have 'micro-suspension', but this just means the carbon fibre soaks up trail vibration like a carbon bar.
Unsurprisingly, the RC30 didn't have any travel either, just straight blade legs. The crown was the same as the equivalent RC35 and the legs are even interchangeable.
On a more positive note, they are good looking lightweight forks that will stand up to some abuse (I still ride my 1994 RC35s).
Not sure what you should pay for them, but let me know if you don't buy them - I might!