What's the bike doing? Is the rear end not compressing to your satisfaction?
Like I said in other thread, you should mess around with the compression and rebound and sag before you go to a part change.
So say it's to stiff right now and you get a softer spring. In a year you become a much better rider and not that spring is too soft. Now you have to go back to what you had, when you might've avoided all of that by just adjusting the compression and rebound.
Sorry to sound like a broken record, this is what my professional suspension tuner made me do. Wait until we got to the extremes of the adjustments before we did part changes.