I generally feel that Rega bias was always a bit on the high side (had Planar 2 & 3 way back when and am happily spinning a P7 now). Not the most precise and the same-as-VTF recommendation seems like a rule to make things simple (as Rega like). It's also stylus dependant as various diamond cuts and polishes have differing groove friction.
For instance the SAS stylus type from Jico works with very little anti-skate whereas Ortofons top-tip "Replicant 100" requires quite a bit anti-skate/bias.
But again don't worry too much and don't feel bad by setting the bias slightly lower than the tracking force.
And since your RP3 is brand-new (obviously) the rubber on the lift/lower bar is as it should be.
Rega arms apply an outward pull even when bias is set at "0" - due to the use of a magnet.