I understand that it will increase the number of impressions that your advert will receive, however I presume you have no control over the where the advert will appear?
So opting in to use the content network would I be putting my advert into the hands of Google hoping that the advert would perform well?
I have some clients who convert 3-4X on content than they do on search--- others that can't convert there at all.
Test the waters, measure, refine.
However I don't know how to track roi there can you help me with that?
I think there is some good in content network that I can't obtain yet.
Before the recent addition of separate bidding-- I have often built Content into a campaign of its own in order to manage the ROI. Now, there is no longer any reason to do that. But, it is still imperative that keywords are broken into logical groupings in order to make meaningful bidding decisions based on ROI.
And do not be mislead by the google adwords reports. In the google adwords reports the reported CTR will still be the overall CTR of complete campaign ( including search and content networks if enabled).
But for ranking only the CTR from search on google is considered.