I bought a BOB last Spring to try out touring and I liked it (both the BOB and the new pastime). For the first few weekend trips, I just hooked up the trailer to my mtb with no modifications. In September, I put a front rack and small panniers on the bike in order to keep more stuff close at hand since it gets to be a pain to untie everything from the BOB just to make lunch. I can install or remove the rack as needed, but the bike is otherwise just my everyday mountainbike.
Then I had a hankering to try out lighter touring without the trailer, so I "roadiefied" my uncle`s old Schwinn mtb over the Winter. So far I`ve only made one trip with it, but I like it too. It`s also fun for paved day rides with the 1.25 tires I have mounted (almost microsocpoic by my standards). My panniers are very small- they worked, but I prefer a little more room. I`ll either get some that are a little bigger or another equally small pair and go with both front and rear. I`m keeping my mtb of course. It`s still my regular ride for local trails and I can hitch up the "chariot" for rough terrain tours. By the way- I`d love to do a mega tour one of these days, but I`m pretty happy with my weekenders. Since I get a lot of three to four day weekends with my work schedule, I`ll probably just keep doing the mini tours and hope for good enough health when I retire to do a biggie. My dream trip is Reno to Guadalajara and back. Anyway, here are pics of my two loaded rigs and links to my two longest rides to date (both four day trips).
http://www.crazyguyonabike.com/doc/gerlachride
http://www.crazyguyonabike.com/doc/featherriver