This one is not all doom and gloom. I must ask are these sites stealing cash from you? if so then yes a Google spam report would be a good idea. But if they are just using content for the Google adsense I would not bother. This can indirectly have many benefits.
I have lots of sites I leave alone if they are using my content for the adsense program. If this be the case Google will likely do nothing and favor your site all the more. Google makes money off your site, they would put a higher importance on it. I am however speculating here. greek39