If you are like me (and I think a whole lot of others), when you start riding roads you will pick up the speed addiction. It is soooooo much fun to effortlessly go fast. Especially since you have an MTB, get something that will slide along sweetly from the get go. The tires with slicks in the middle and knobs on the sides are not fast, are not good of road, and are more hype than happy. If something looks slow, it prolly is.
If you are looking at a Specialized shop, try the Sirrus, which is much quicker than some of the others, but try a Secteur as well. It is a relaxed geo alum road bike. The Allez is the more racing geometry. Then you can answer for yourself and by feel whether you want road or hybrid.