Be aware of a few other potential differences, especially that frames' top tube lengths may be different between road bikes and hybrids designed for flat bars. If you convert a hybrid with a long top tube to drop bar, you might find the reach to be a bit of a stretch unless you use a very short stem. Many bike companies have frame geometry charts posted online, so you can compare to find out if this would be a problem for a specific bike you're considering.

Also, you may find the cost of a hybrid plus conversion may cost more than buying a road bike in the first place. Below is a list of items you may wind up replacing to pull this off well. (You may not need all of them, but each of these items is a possibility depending on what bike you start with.)

Handlebar
Stem
Brake/Shift Levers
Bar Tape
Brake Cables & Housing
Shift Cables & Housing
Road Front Derailleur
Road Tires & Tubes

...and you'll need to make sure the parts you select are compatible.