Google+ is an engagement medium. With that in mind, some comments about your post.
I think your statistics also need to look at "Non-ad blockers" who were given a similar choice as the "ad blockers": select to opt into Ad-Lite Forbes. Then you would have a balanced comparison and have offered an incentive to those who weren't trying to deny you your revenue. My feelings after twice reading your articles are that as a non-ad blocker, I get no reward except an undiluted onslaught of flashy jerky changing ads.
Secondly, I wholeheartedly support the additional areas you are investigating as described towards the end of the article. I hope you will, in fairness, present those results with unbiased statistics: what is the bandwidth usage of the ads? How many users click away in disgust from the onslaught of Forbes' online ads? Do you do any exit interviews with these users?
Finally, the chart (above) showing percentages: From a statistical standpoint, I find almost little difference between the three groups. Obviously there's a 5% difference of technology readers, but even that is not huge and somewhat expected as you pointed out in your article. Percentages mask population size. Are each of the three groups of equal size? how many in those groups? what does this chart really tell us about the experiment. (Is it the message to your contributors that you aren't losing significant numbers of readers by demanding removal of ad-blockers?)
Why are ad-blocking readers responding to your request? Is it a positive response to the view that you are taking their concerns seriously? Or is to try a "Ad lite" experience? What's the stickiness of these people after the month trial is over?