Seriously, what you have to decide is if you enjoy riding with this group. If you want to continue, I would get a TT bike. It will be more fun and you will fit in better. And why not take on a new challenge by learning to ride a TT bike. You may or may not be faster. A lot depends on how well you produce power in a more aero position. In the drops of a road bike, you will produce more power. My TT bike weighs around 16 pounds. So TT bikes are not necessarily heavier.
I assume this group is comprised of triathletes. And depending on the event, they may be allowed to draft in competition so riding in a group on tri bikes makes sense. Good luck.
Last edited by Hermes; 09-14-11 at 05:19 PM.