Actual experience with Öhlins or general experience with this platform?
It shouldn’t be too stiff for street use and normally, you’d only need much stiffer springs if you’re running semislicks or better.
On the other hand, look at your recommendation and the regular spring rates typically used. There’s a difference, but not very big. 20%.
Now, how could Öhlins explain the regular 70N/mm springs they use in the rear?