So buy the FX and replace the saddle! Sounds to me you already know which bike has stolen your heart. Everything else is just trying to justify it.
I could never, ever, ever buy a bike that I didn't like the look of. I'd resent even looking in its general direction and I'd never want to ride it.
Maybe you should! I looked for a new bike for months before finally deciding on the Cannondale. It was originally a brand (and model) I'd decided against, but after riding it, it totally stole my heart (and with it, all rational thought related to budget).
I'm sorry to be the one to tell you this.. but it will only get worse. You're on a slippery slope, my dear! Buying the bike of your dreams is just the start. Once you've got the bike, your dreams will be filled with rides on the new steed. Then, you'll wake up one day and realise the new steed needs new tyres, or maybe an updated doodad or better widget. Just embrace it, it's easier that way
Max