I'm almost 20 and I've been riding road bikes since I was 17. I go on long solo rides often, and a couple of the bikes I've bought have been in your budget range, so maybe I know where you're coming from. Hopefully I can help.
Is a road bike worth getting for the "recreational rider"? Depends what you call a "recreational rider." Someone who recreationally rides 10 miles once a month probably doesn't need a road bike in your budget. I consider myself a recreational rider. I don't race, I usually ride road solo. I put a minimum of about 50 miles a week on my bike, and that's when the weather's bad, I'm busy, and school work is piling up. Most weeks during the summer I put in more like 200 miles with a few weeks of long rides that's more touring than anything else. I think a road bike is worth it for the kind of road riding I do.
How much do I need to ride it to make it worth it? Depends on how you feel. If I paid between $1,000 and $1,700 I would have to ride it at least somewhat regularly. I know/know of some people who spent a lot more than that on a bike and only bring it out for a 50 mile charity ride a couple times a year.
How much faster and efficient is a road bike over a hybrid bicycle? A lot.
What brand/type of road bike should I get? Depends on what you want to do. There are a ton of choices. This year I bought a Surly Pacer. Without the decals it's a plain looking bike that doesn't look too appetizing to thieves around campus, it can haul groceries, it has fenders, I can put bigger (32c) tires on it, and it eats the road fairly well considering. You wouldn't want to race it, but I use it as my car and as my road bike during the school year. I have room for one bike in college and the Pacer does a lot of things ok. Get a more performance oriented bike if you just want to ride. Something like a Trek Madone 3.1, a Specialized Allez/Secteur, a Giant Defy, Cannondale Caad-something or a gazillion others. Talk to people, get opinions, research and test ride. Used bikes can be a good value, just make sure the bike fits you and is a reasonable price. Any road bike in your budget is going to work for you way better than your hybrid.
If you want to go on longer rides budget in things like clothes, shoes, and bibs if you don't have any. They're worth it.
Last edited by ConradNaff; 09-23-11 at 10:12 PM.