Just a quick note re plugins leaving traces behind: We actually provide an entire companion plugin called Wordfence Assistant (also in the official repo) that lets you remove our data without having to reinstall Wordfence. And of course Wordfence has the built in option to completely remove all traces - see the bottom of the Wordfence options page.
We had some issues with LiteSpeed web servers when we first launched, that's been resolved.
Also we now fully support nginx and PHP5-FPM configurations and Falcon will auto-detect if you're running that and direct you to a page containing the configuration you need.
Falcon is maturing nicely and we're working hard to make it the best caching option in the business.
I'd also add that our scanning is far superior to anything else out there because we are a WordPress specific product and we maintain a mirror of every plugin, theme and core file ever released along with SHA256 hashes of those files. We compare your files against the known files and that gives us a way to detect zero day infections and exploits which other products (including some very pricey one's) can't detect - and of course you can see the file changes and repair your files with Wordfence.
Regards,
Mark.