Chrisp72 - exactly why I decided to buy this bike to replace an 1995 Trek 520 touring bike and not put those bags on my carbon road bike. I tried it for an 85 mile ride and everything fits fine, but I weigh 225 and my weight plus those bags is right at the warranty limit for the carbon bike - and probably above the smart limit for the wheels I use on the carbon bike.
I'm pretty sure the steel Jamis frame with be fine, plus since I'm not camping/cooking, that rear saddle bag has mostly clothese in it, with the heavier stuff next to the seatpost.