Hello, Its Juano9z here. This month with Google Adsense, I got a surprise. My revenue from searches had increased and people who search with my bar tend to click on the ads. Actually 26% of the searches resulted on a click. I thought about making my bar very visible so I got more searches, but then I saw that I had x3 number of clicks on the searches than on the ads, but the ads had generated more money than the search. This month I have earned $6 and scarcely $1.5 came from the searches. This means that though I had a huge CTR in searches, it didnt gave as much money as my low CTR in ads.
The reason why you are not paid as much per click (in the search) is because the click through rate is higher, therefore, the amount the advertisers pay per click is lower.
If you didn't have adsense search on your site, do you think your ads would have been clicked more and they would have earned $1.5 more in the month? If not, then it's better to let adsense search. I also use it on several of my sites, and the earnings are not great, but it adds up at the end of the month, and so, why not.. Also I make adsense search give only results from my own site, so the users either click on an ad in adsense search or go back to my site with a result link. I don't let adsense search to give worldwide results, only from my site(s).