Mr md902man,
I surely hope you do report them if they are not guilty they will rightly put up a legitimate defence.
everyone knows it is going on and yet a malaise exists where people just let it happen.
the PPL guys who often do the flying are well known for it, and yet only circumstantial evidence exists.
dont be put off by the fact that you have to collect evidence, I believe it is worth it and I would do the same.
good luck
CF