Pollux of course Cloudflare is a completely optional suggestion. I've been using Cloudflare from since 2009/10 beta development/testing period for some website properties. And I've used prior to that since Cloudflare's beginnings started with the "The Honey Pot Project. See: https://www.cloudflare.com/our-story/ (or wikipedia etc).
People try to demonize and scare others about Cloudflare all the time are usually uninformed about 3 things, 1) the company itself 2) how Cloudflare works and 3) that they are already sharing the same imformation they worry about and far more to other tech companies who have be come a more generally accepted 'norm'.
If one is worried about the type of data passing over an encrypted connection on a web forum they have a bigger problem than Cloudflare. You are using either Google (Chrome), Mozilla (Firefox) or Apple (for the most part) to read this right now. Where's the worry there?
Don't talk about Facebook, Twitter or IG (also fb) ...who we know for a fact track you so heavily that they resell ads so targeted that you can buy ads targeted to people who have traveled to Las Vegas recently, who are interested in guns, between the ages of 18 - 35 who also have visited specific websites recently and who don't speak English. And in less that 5 mins.
It's going to be your individual decision on something like this. Also based on the sensitivity of the data in question that you are hosting.
But remember CLoudflare didn't launch offing SSL encryption, but its natural to offer free ssl compatibility given other solutions such as Let's Encrypt, AutoSSL, etc and the trend to encrypt rightfully pushed by Google and others. The whole SSL industry was far more of a big scam basically paying for reputation to verify something so simple. Another topic.
I would encourage one to do their own research. Arrive at your own choice. Also don't receive your cert bundle download via any email (esp Gmail) if worried like this. If you are dealing with highly sensitive data then Cloudflare would be the very tip of huge privacy sharing and policies iceberg.
Also setup to pass PCI and other compliance which can be achieved with and without Cloudflare: See: https://www.pcisecuritystandards.org
Your only safe bet if you do have such highly sensitive data or preferences is to setup everything by hand in that sense, avoid the cloud and avoid almost all 3rd party services.
Edit: Other good reads:
Cloudflare’s Transparency Report for Second Half 2016 and an Additional Disclosure for 2013.
