Thanks for all the feedback guys!
This was definitely not an easy decision for us, we don't like ads and were looking for alternatives for quite some time. We spent over 5k USD on server/domain/ssl/anti-ddos/backups since we took over the forum (even though participation has fallen since the devs are working on their stuff, lurkers are plenty).
We pretty much need 500 USD/month to cover all or costs. We don't expect to make that with adsens, but it's at least something.
Has anyone here read the topic I posted regarding Bitteaser, it seems this is exactly what Bitteaser is offering that you are in fact looking for, and if you can make money in the same time, then why not instead of considering an expensive Google solution!!
https://bitsharestalk.org/index.php/topic,17940.0.html
Thanks. Reading up on it!