My WP shock came with a 120 nm spring (which I believe is the same rate as the stock Ohlin's spring) and it was softer than a 100 quid duck down pillow from John Lewis.
I was told the stock BM spring is 130 nm. WP heaviest spring was a 140nm, which wasn't going to change my world. So the WP one was thrown in a skip and I got a one off 175nm spring made by
http://www.dfaulknersprings.com/acatalog/Specials.html good service and 4 years on the spring is doing its job.
If buying again (aiming for 120kg min loading of rider and gear) I'd go for a 180 nm or more.
We just got back from NL with their stupid speed bumps. On 50 mph roads we were scraping it coming off them gently two up, 170kg load, (and had to go down to 25mph with loaded paniers and topbox on top of that weight)