Swapping half your springs out for springs from a WR 250 is supposed to work pretty well. I'm gonna try it next summer. In the really tight stuff it does matter. for sure.
This is not an ideal solution. I tried this with YZ250F springs. It slips under a heavy load. Reduces your torque and increases wear on the clutch. I want more torque, not less. And the slippage cannot be good for clutch life. Probably makes everything run hotter too.
I have a solution to the stiff clutch on the WR. It's a more expensive approach but without the negative side effects. There are two steps you can take.
Step 1. Add an ASV C6 clutch lever. It is not advertised as an "easy-pull" lever and does not have multiple cable connection (leverage) points but it has a good sealed bearing at the pivot point which makes the pull easier without altering pull distance. If you ride open trails, you can stop here. The best thing about the C6 is the adjustable lever (for reach) and the smooth, slop-free feel in the lever. Feels almost as good as a hydro-clutch. 1-finger pull all day long in the open. If you ride ignorantly-tight woods trails, and tend to get arm/hand fatigue, then proceed to step 2.
Step 2: Add a Moose Easy-Pull Clutch System AND a custom clutch cable. On my 2013 WR, I hooked up the Moose gizmo and then measured the added length that it put in the system. Requires a 5.25" shorter cable and a smaller cable end (OEM is too wide and grabs inside the Moose housing). Added length can vary by bike so hook up the Moose gizmo first and then measure before ordering your cable (from Motion Pro or Barnett). Clutch pull is much lighter than the hydro on my KTM. Waiting on custom cable.