Come on guys, please stay calm, your drop of sales has absolutely nothing to do with Cloudflare. I tried everything as a free user, and even my downloadmanager kept working...
I use Cloudflare by myself and very happy with it. And since Mates uses it too, the website hasn't gone offline. Not too bad isn't it ?
Cloudflare is basically a bunch of servers spread all over the world. They cache pages and if for instance a guy in Australia wants to visit FM, if there is a cached pages on the Australian server, he will download from there. It is simply a nice tool to speed things up and to save bandwith. Also, if a page goes offline, Cloudflare will show a cached page if they have one (works only well with static pages)
But there is more, since all your traffic is routed over Cloudflare servers, you suddenly have an IP of Cloudflare. If (and only if) your settings on Cloudflare are perfect (for most sites they are not), there is no way for a hacker to attack you as he has no idea where you are. In fact, if done well, you are completely anonymous.
They even have their own Robert King doing a crusade to all the bad people who use the service to stay anonymous (funny detail : the real Robert King is using Cloudflare too, and I must congratulate him ; his settings are good so no way to launch a successful attack against stopfilelockers)
But, and here comes the most important : being one of the largest server companies in the world, Cloudflare is much better equipped to block
DDOS attacks. In fact, I doubt one attack ever succeeded.
As an website administrator, you can choose how high you put your security level. Mates choose the highest "I'm under attack" one and that is up to him. However, I would use the second highest and just change it when there is really an attack - users will not notice that you use Cloudflare this way.
If you want to know more about this subject, please visit their blog on blog.cloudflare.com
If you have a blog by yourself, you should consider to use it. Best of all, it is free