5 years ago I did the Northern Tier with our daughter. We both used road bikes and trailers. She: Burley Nomad. Me: BOB. I'd say the primary downsides are additional weight, and lots of wear on the drive train and brakes because of the heavier loads. Face it. Road bikes are not really designed to pull that much weight for an extended distance. But, if I were to do it again, I'd definately consider the same arrangement before I invested in a touring bike.