Hey Reid-
I was in a similar situation (albeit a sight younger) a few years back after a knee injury put a stop to my running and I decided to reexamine the cycling world. I too started with an fx--and coming up from vintage steel bikes, I know that thing feels like a speed demon and if flat bars are what you're looking for, then by all means they're great bikes (though perhaps consider a used model, they're respectably durable--I just sold my 2010 fx at only a 38% depreciation from MSRP
).
However, the fx is as much a city/commuter/cul-de-sac cruiser as it is a rodie (though really, more the former): the bike is a fine machine, but just isn't very
serious, you know? -If you want your $500 to go its farthest, you might consider a used roadie. I see your in Kansas--where I'd imagine there isn't as lush a used bike market as we've got on the west coast, but as an example:
http://seattle.craigslist.org/see/bik/2996827327.html ,
http://seattle.craigslist.org/tac/bik/2998600464.html . or in your neck of the woods:
http://topeka.craigslist.org/bik/2979236972.html,
http://ksu.craigslist.org/bik/2986823877.html,
http://lawrence.craigslist.org/bik/2958950485.html ....etc, etc.
If you could entertain the possibility of going for a roadie in lieu of a fusion you stand to get a lot more bang per buck. Also speaking as someone who bought their fusion bike while living in a rural area, which I know most of Kansas is, you should REALLY consider--because having a nimble upright city bike in a big open place, is kind of boring. Go to some lbs' -try a few different styles of road bikes, figure out what fits you, what you like, etc. Then when you find something on the used market, try and get it looked over by a bike mechanic (this can be super important when buying a nicer bike with some miles and you're not 100% what you're looking at), and chances are you can walk away with a lot more than what you'd get with a new $500 bike. PLUS, if you're not buying from new, you won't ahve nearly as much depreciation from purchase, so if you decide after a while it's not for you- you can sell it on at a much smaller net loss.
Hope my rant's been of help to you!
-Ben
Edit: your last comment showed up after I wrote the above...so, yeah- disregard that, congrats on your purchase & have a blast!