I smoked a pipe for several years. You may not inhale as much or as often with a pipe, but when you do, you’re getting the full monty, with no filtering going on. In addition, tar can accumulate in the pipe bowl. If you inadvertantly tilt the pipe upwards, you’re going to get a dose of one of the foulest substances imaginable. The risk of mouth and throat cancer is (I believe) heightened with pipe and possibly cigar smoking, but I can’t provide a cite off the cuff.
They really can be a pain in the ass to keep stuffed and lit, and you’re always fussing with the bloody things and having to clean and scrape them.
I don’t have the cite online, I saw it on the Custer’s Last Stand episode of Battlefield Detectives, but they were able to tell that one of the troopers was a pipe smoker because of the way his teeth were messed up.