Ok Ok, I've been busy so sorry for the delay
My understanding is that progressive springs are not the great leap forward they're made out to be.
The theory is that the firmer part of the spring absorbs heavy loads eg braking which leaves the lighter part to deal with bumps etc WHILE braking.
However, in practice the weight of the bike uses uup the soft part, leaving you with bog standard linear springs but of reduced length.
Better to go for the linear springs with oil to match, but give Roger at Revolution a bell coz he's really helpful and very happy to chat, even if you're not buying the bits from him
Ben