For web hosting enviroments LFD is great, sometimes port scan gives a little trouble
with false positives, so you need to keep an eye on them.
CSF is very nice, and has evolved since it's creation, so in combination with
LFD they do a great job.
But... you have to keep track of the logs, if you use mod_security rules, you could block
forever everybody if a rule doesn't like a website (not just http block but ip blocking too).
Anyway, as people already told, they're different, but CSF+LFD is totally recommendable.
cheers!