They sure look cool onstage at the Forum, but man, those things are huge!
There was awhile in the early 90's, when I got infected with 'rack-itis' and was lugging around a case with a head and 6 rack spaces. Also, some time with a 16 space Mesa SUS-4 rig. Boy...I learned my lesson. Lugging that around almost killed me.
If you use a rack, don't go larger than 6 or 8 space. You'll regret it.
As a matter of fact, if you use a head, get a 2 space soft rack bag for 1 FX unit and a Furman powerstrip. It's so much easier to move around.