Although FH3 has 3 ballads (out of 10 songs), I think it really rocks out (and hard)!
It's got some mean big gad grooves, man! Although it differs stylewise from their first two albums, I still love it. It's HUGE! And it rocks.

Now Cat5 is a different story. Quality songwriting, no question, but overall a more poppy sound, it doesn't rock very hard. I'm definitely not saying it's a bad album, just ... different. More mellow.

So I'd say, if you like the first two albums, get FH3 first.
If you like that one, you can try Cat5 ... but I suggest you listen before you buy.

Rocket!
(waddaya mean do I like DL?)
Sven.