I've played some very nice chambered instruments, but I thought I'd post up a disadvantage that I've noticed: some chambered instruments don't exactly cut through a mix as well as their non-chambered counterparts.
They tend to allow a lot of harmonic overtones to bloom, and cloud the fundamental tone. This is great when you have a lot of space in the mix that you need to fill (and fantastic when you play by yourself), but not so hot when you're fighting to be heard in a dense mix or less than perfect stage setup.
To me, some chambered guitars sound like they have reverb permanently on. Great for a while, but there's nothing you can do if you need to turn the reverb off...