I test rode a couple of buells before I test rode a guzzi v11 lemans, the buell (firebolt) was fun but I felt it was too small, my head felt like it was over the front wheel. I felt more comfortable on the guzzi, and liked the motor and looks better.
I'm an engineer by trade and actually was set on the firebolt cause i like Erics engineering ideas, but to hear the bike run (the stock pipes sounded like crap) and actually ride one turned me off.
Im 5'11" and about 220lbs, If your 5'8" and 170lbs a firebolt might fit...
I am in love with the lemans and its a keeper, no serious issues to date.
Have you considered a KTM? Their super motard, adventure, and Duke bikes look pretty good, they have excellent engineering. I have a KTM 450EXC dirt bike that I abuse regularly, Im impressed with how well that baby performs too. Should have bought stock in them about 10 years ago.