A major concern, as I see it, is bike fit.

Your comfort on a road bike will be much more sensitive to bike dimensions and the like than for your hybrid.

With a used bike, you have limited options for a good fit. If you are not familiar with the concept of a bike fit, folks spend a lot of money and time fine-tuning a bike to their riding style and dimentsions.

Things like the proportion of your body - short legs, long body(me) or long legs, short body, make a real difference in the brand and type of bike one might purchase.

You can get a really good new bike for $2-3,000.

Personally, I would go to a really good local bike shop and see if you can find someone very knowledgeable, explain your riding desires, and see what happens. A really good shop will take a lot of time with you on these issues, as well as your body type.

One of the things you are buying, besides a bike, is a good relationship with a Local Bike SHop. (LBS)

I would not buy used on my first road bike. Too many things can go wrong, and your expensive road bike may end up hanging in the garage if you don't thoroughly enjoy how it feels.