I would guess that 99% of internet users still have no idea what an "ad by google" is. Most still don't even know they are clicking on ads. Haven't you ever had friends and family ask how you make money on the internet, and when you tell them that you put Google ads on your site they just look at you with a blank cow look? (these are regular users of the internet, mind you ... they just don't have any idea, and nor do they care really, how people "make money" off the internet)
If you search the fourms you'll see that like anything else; "it depends". I have sites that would tank if I put YPN on them, but I have one site in particular that does 10x what it did with adsense now that I put ypn on it. If you can keep your CTR the same, I would say that YPN has a much better CPC *for now*.
I'm finding that the cpc is alot higher but the ctr alot lower so it really isn't making too much of a difference.
I would have to agree with what is being said here. While I get more clicks overall on alot of my sites from Google the sheer difference in payout from YPN makes their system much better for my sites and the profitability of them overall. I am building a new site and I am going to try a mix of YPN and Google ads by placing one or the other on individual pages to see which is working better for the site. Comparing how they do on your site is going to be the only real true way of knowing which is more profitable for you. You may find that google does better on the website or that yahoo does or you might find out that placing one or the other on certain pages is the way to go.
I am new to Adsense and YPN and just switched to YPN. After using both for only a few weeks my profits are much higher with YPN. Granted, it took a little more tweaking with YPN but overall it is working better than Google.