Oh, I've downloaded Caddy and used it a few times, I love it but haven't switched anything to it yet.
To me, the killer feature right now is that I can just drop it in my /usr/bin directory and have a performant HTTP server in the current dir with just one command. I don't use the LE integration (even though I love the feature) because I haven't deployed it in anything outward-facing.
One small nit would be that I'm not very clear on how the LE fetching is done (where all the files are placed). The docs do mention this, but I left with a feeling that I was still not very clear on where the files go after reading it. Other than that, great job on Caddy!
I use simp_le for that. I more meant "I'd have paid a CA 10% more for automation", but that ship has sailed now that LE has launched. I'm probably not going to be using anything else any time soon.
I wrote a server that does this. Would be happy to have your feedback sometime: https://caddyserver.com - here's how it works with regards to Let's Encrypt certs: https://www.youtube.com/watch?v=OE5UhQGg_Fo&t=32m