I'm not a racer either, I just have a plain road bike, not even a very racy one. But when I look at my bike after a 100 km ride and tell myself "did I just spend four hours on this?" I'm always amazed at how comfy it is despite what it looks to be. That tiny saddle, the handlebars lower than the seat, these small small pedals... and yet, I feel great sitting on it, and actually even better when in the drops (the lower part of the handlebars, so a bit more stretched out).

Sitting on a bike is not like sitting in a chair, so "chair sitting norms" should not be applied to sitting on a bike, not even a hybrid one. For example, your hips are supposed to be slightly tilted so that you're sitting on your sit bone, not your bum, that will be much more enjoyable. Being upright is an issue if you're riding in big traffic a lot and you want to have a more all-around view (including above the cars; I also find I look heavier on my hybrid, hence more threatening to cars, which is good in a way!!) but for open road riding it's not necessary, you do get quite a good view (including of the horses and trees and rivers along the way!).

So my point is: do not judge a bike by how it looks compared to the other bikes you've used in the past or to what instinctively seems comfy. A road bike is a totally different experience (more fun!!! to me at least). Go on and try one, then two, three! Of course, it may take you a while to get totally used to it, some pain (not sharp) and soreness is normal as you start because you are using new muscles of your body (even the upper part of it). But a good bike fit done by professionals should take care of most issues so that after a few rides you feel about as good on the bike as you would in a Lazy-Boy, or, in my case, better.

Also: this is not only about speed: it also translates in the effort you have to put in to just keep going. A more aerodynamic position will require less effort for you to ride, especially in a headwind. The position is at least as important as the weight/tires/frame geometry component in explaining why a road bike is faster...

I don't know about the precise specs of those two bikes (the 1000 and the 1000c) but in my opinion you already have a "comfortable" bike, the mountain bike. If it suits you, you should definitely not outrule the 1000 model for now. Be bold: you'll be fast.