A road bike will likely help you go a bit faster. Fast enough to keep up with the other riders? I don't know. It depends on your fitness and their fitness. I followed a similar path to yours, and even with a road bike, I had to work pretty hard at first to keep up with people who had been riding for a while. But, in the end, it's the journey, not the destination, right?
Ride bikes are fun and while I think bikes like the FX are a great choice for many riders, road bikes have their advantages, too.
As for good beginner bikes, nearly every manufacturer offers an entry level bike. Buy the best bike you can afford that (and this is key) fits you. The WSD designation is typically less about height and more about proportions. So, I wouldn't necessarily rule it out. Try as many bikes as you can and try to find an LBS that is willing to work with you on getting a bike that fits and is within your budget.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher