Re: Road bike or tri bike?
Ultimately, the only one who can decide what is right for you, is you.
But, I went through much of the same decision process earlier this year and here was the factors that went into my decision.
A tri bike is designed and built to be ridden in the aero position. That provides two advantages - better areodynamics/less wind resistance and the geometry also means that you use different muscles than you do on the run, meaning you should be better prepared to come off the bike and run when using a tri bike verses a traditional bike. That's why even if you add clip-on aero bars to a road bike, you still don't get the full advantages of a tri bike.
I'll also note that when riding aero, you weight is mainly on your forearms, rather than your hands. I find it a lot more comfortable, but I've never done any extensive mileage on a road bike.
Tri bikes work well when you are racing alone, as opposed to a pack/peloton. Tri bikes don't handle nearly as well as a road bike, its more difficult to get to the brakes quickly and you just don't have as much control with your weight shifted forward. Therefore a lot of bike groups either don't like or won't allow you to ride in a pack when on your aerobars. If you ride aero in a pack, you're putting a lot of trust that the guy in front of you isn't going to have to brake quickly or make any other unexpected maneuver.
Tri bikes also don't climb as well as a road bike. Most of the time when you are climbing a serious hill with your tri bike, you'll come out of the aero position. And the tri bikes were designed to be ridden in the aero position.
In general, a road bike is a more versatile machine. The advice I came across time and time again was that if you're not sure you're going to stick triathlon, then get a road bike. There are a lot of people who do triathlons with just a road bike. If you do get a tri bike, and decide you don't like triathlons, its not like you won't be able to use the tri bike, but there may be certain situations where it is less useful. Also, if you live in a hilly/mountainous region, you may want to consider going with a road bike anyways because it will be more useful on more rides.
Now, with all that being said, I bought a tri bike. Even though I have not yet competed in my first tri, I'm already planning to do a Ironman next year. And there is a good chance I'll pick up a road bike next spring just to do rides with some of the really good biking groups around here. But that's me.
When I was looking, the Felt S3 was well reviewed. It sounds like it is a fairly typical aluminum frame with some good quality components.
Good luck,
Mike
