Wrist mount DEFINITELY beats console for convenience of availability of information.
I used to laugh at people that suggested two computers, but I was never happier than when I dove three-dundantly... I had my old console computer (Véo), then my IQ800 on the left wrist and my hubby's new toy on the right wrist (I'd picked it up when it came in, he wasn't diving with us up north that weekend muahahahaha). One on each wrist was actually incredibly cool, too; I never had to even LOOK for info, it was just always there.
So now I don't laugh about backup computers, even for basic rec diving. =-) Let's be honest, if you're hooked on diving you'll probably have two within a year or so ANYWAY...
Amy