I know of way more than 5 cases of relationships making it post drum corps. I can think of almost 10 where people have gotten married as a result of meeting someone in the activity and many others on their way. I can also think of some that ended in a giant mess. I think people in drum corps enjoy relationsips with other drum corps members because there is an understanding there. You understand the activity, you are going through the same things together, so on and so forth. I'm not saying people outside the actuivity can't understand this, but it just seems easier I guess with a fellow corps member. Not everyone finds it important to hook up on tour either. I have a bunch of friends who actually won't hook up. They are focused solely on the show and the competition and say they don't want to be 'distracted' from the task at hand. To each their own. I do agree having a relationship does cause drama though. Especially if the relationship goes south, however, it's a test of maturity. If you can handle the drama and not let it get to you, fine, but it gets frustrating when the off field relationship trouble is brought to rehearsal.
As to whether they are worth it, I think that is a case by case thing. Communication on tour is really important because many tour relationships involve people living on different ends of the US and sometimes in different countries. So a lot weight on whether it's worth it is up to the two people and their commitment to making something work. Personally I think it is worth it because I'm with someone amazing who I met in 04 and have fought long and hard for. :) We're making it work at a crazy long distance. So to me, it's worth the work and plane tickets and ridiculous time apart. Some people don't think something like that would be worth it.
Now if both people are all for a tour fling, then by all means! Gotta love a fling! Especially on tour. :P
Just my thoughts!