We have rented with them twice (2 separate trips). We didn't do a group trip, but just rented a canoe to go camping in the National Park. They are helpful and were recommended by the Park Service. Sometimes the service could be pretty mellow and they tended to service phone calls before the folks standing in front of them, with was rather frustrating at times, but oh well, we're on vacation, so I guess we need to relax!
We didn't have a roof rack but we put the canoe up on foam blocks and that worked fine. Just bring along a few towels to protect the roof of the car from the screw heads on the boat - they can scratch the top of the car (I know from personal experience). You get the boat, tie downs, dry backs, paddles, life preservers. We will go to them again!