Looking back on my expierences, I have very mixed feelings. Looking at marching bands in secular schools, I see a lot of problems:
Uniforms: often the young ladies are forced to wear pants, or worse! In some cases, the costumes the girls in the color guard (flags, rifles, dance, etc.) are almost non-existant!
Music: almost never is proper for the Christian! Does not praise God!
Dancing: many bands have actions that are downright vulgar. There is one (here in Chrarlotte, NC) that was banned from the Christmas parade becuase their actions were so vulgar that they offended the community. If you know anything about Charlotte, you know that is saying a LOT!
I went to band camp - I know that more than music and marching is practiced or learned! In fact, one of our 'adult' sponsors told us how to sneak out of the dorm we were in w/o setting off an alarm and which bar we could go to!
Now, despite all of these bad things, I firmly believe that everyone should at least try to learn an instrument, but I cannot say that I support a secular school's marching band!