.9, and .95kg/mm are linear spring rates, so I assume he is in favour of linear springs 
(they are called linear because they always compress at the same rate.. i.e for every 0.9, or 0.95Kg of load on the spring, they will compress 1mm...in a linear fashion hence the name!.
Progressive springs spring rate changes depending on how much they are compressed and so are more forgiving on general riding (softer), but as you attack corners they compress more to a firmer spring rate...so they are progressive.)
sorry if thats teaching granny to suck eggs material, just incase you didnt understand the basic difference between the two
(they are called linear because they always compress at the same rate.. i.e for every 0.9, or 0.95Kg of load on the spring, they will compress 1mm...in a linear fashion hence the name!.
Progressive springs spring rate changes depending on how much they are compressed and so are more forgiving on general riding (softer), but as you attack corners they compress more to a firmer spring rate...so they are progressive.)
sorry if thats teaching granny to suck eggs material, just incase you didnt understand the basic difference between the two