I'm using Cloudflare + Heroku to host https://www.gitignore.io [0], but I'm not using a LetsEncrypt certificate. I'm just using Cloudflare's Universal SSL[1] certificate. So far everything with Cloudflare has been amazing; they even prevented a 99 million+ request DDOS attack on my site a few years ago.

[0] - https://github.com/joeblau/gitignore.io/wiki/System-Architec...

[1] - https://blog.cloudflare.com/introducing-universal-ssl/