Hi MeGustaMusic,
Yes, I agree. However, there are a lot more such services besides AdRev. The only solution is joining all such services, just to avoid the unpleasant surprise that someone else registered my songs before me.
This may seem like the logic thing to do for someone with lots of sales, but for authors who have ZERO traffic on AJ (like me) I wonder if it’s worth it. I mean, nobody can find my songs on AJ, I would be really surprised if AdRev found any of my tracks on youtube 
Just sayin…
Anyway, thanks for the replies guys, after reading this and other similar posts as well, I think I made up my mind 