Have you test driven enough to know the suspension is too harsh for you? If so, you could try to find a dealer that supplies Mountune parts and get the springs dealer installed (and warrantied?) as part of your purchase price. ~1 inch lower, but progressive and more comfortable (at least "everyone" says so).
Another option:
1. Get the FiST
2. If the harshness still bothers you, swap down to lightweight 16" (or 15") wheels and tires. Firsthand I can tell you 16" wheels are a significant improvement in ride quality. It is still firm and bouncy, but harshness is reduced (probably not more than swapping to stiffer, progressive springs)
Another option:
1. Get the FiST
2. If the harshness still bothers you, swap down to lightweight 16" (or 15") wheels and tires. Firsthand I can tell you 16" wheels are a significant improvement in ride quality. It is still firm and bouncy, but harshness is reduced (probably not more than swapping to stiffer, progressive springs)
But yes, 16s I'm considering as well. My eye was just drawn to Oranges-in-the-rear as a potential first stop because, well, it's dirt cheap and super easy to do. I'll try to keep my speculations down to a dull roar until I actually get some seat time though.