I tried it for a while and it didn't really help with my bot issues, so I turned it off. As far as AdSense, I seem to remember you're supposed to turn off some feature called Rocket Loader if you're running AdSense. But that was a long time ago; dunno if that's still the case.

I use it for a few of my image heavy sites, I see no "apparent" adsense issue relative to my non cloudflare sites.

Because it's hard to do AB test with it, since the DNS is through cloudflare and there is no easy way to test the AB without really knowing what is behind the box on and off. I am not going to switch my DNS often just to test this.

It catches "some" of the bot attacks to but relatively few, I think it tries to be lenient most of the time to avoid taking out real traffic, I still have all the layers of protection on the origin server with wp-admin, comments, etc, files that get hammers all the time. So I guess it probably does not protect against all the bots vs adsense neither.

@netmeg, from what I saw that rocket loader is still in "beta" mode.

I feared that it didn't really help with bots, bad traffic. And I wasn't sure how much it helped with speed. One of my competitors uses it and I still beat them out in certain speed functions.

The thing that really made me hesitant to use them was changing my DNS over to them.

Incapsula is "reported" to be good for security, but they charge a lot more money. I think 2T limit per month before they try to bump you beyond the 299 package and I think you dont have to change your entire DNS over,

I was going to use mod_security, but every time I've used it it ends up taking out real traffic or blocking legit site functions.

Tried it for awhile and didn't see any effect on revenue one way for the other. Stopped using it after awhile.

I use CloudFlare for my two largest sites and with everything turned on (including Rocketloader) I've seen no appreciable gain or loss in AdSense revenue after making the switch. I've been using them 6+ months and moved from the free plan to the basic paid plan for those sites. Since I have forums on both sites I like the extra protection offered by CF so I plan on being a long term customer.

The nice thing about CF is it does all the processing before bad guys even get to my server. Granted it doesn't get everything, it does a good job of detecting things like fake Googlebots etc. that I couldn't do on my own. And you can set rules, I still have to manually block some IPs for crawlers like LinkDex and ia_archiver.