Well, I, too, started with a comfort bike, but soon wanted more speed. I went from a Trek Navigator 2.0 to a Trel 7.5 FX. What a difference!!! But it did not take long to lust after a road bike.....I now have three road bikes. I must admit that the road bikes get most of the miles I ride. Much ro my surprise the road bike has turned to be much more comfortable for me than I ever imagined.

I do understand your reluctance to make a purchase. Perhaps you can find an LBS who will take the time to give you an initial fit on both styles (the LBS I use is pretty dead this time of year and are willing to spend loads of time with a customer who may not buy) and a test ride. With some knowledge gained through this, you will be better prepared to go look for a used bike that will end up at the LBS for repairs, adjustments, and upgrades.

Good luck with your search and enjoy the ride,
P2