Congrats on the new bike. I made the transition from MTB to Road more than two years ago. First off...stick with the Thomson...it's one of the best made...light and strong.

Switching to road gives you several new different positions for your hands and body. Don't expect that you can immediately ride in the drops for hours without working up to it. When I begin "training up", I focus on riding on the tops and hoods, as relaxed as possible. After I build strength in those positions, I start throwing in time in the drops, a few minutes at a time.

Enjoy your new bike. Hopefully it will give you years of troublefree pleasure!