Mounting ballasts

As I read this I was about to attach two electronic ballasts to the back
(outside) of my hood.  Any reason I should reconsider and think about
mounting them to my stand?

>I am putting the finishing touches on a custom canopy for my 75g, (thanks
>to George and others for the plans and ideas). It will have two 48" shop
>lights in it, with the ballasts located in the cabinet beneath the tank
>(can you say "massive-trunk-o-wires"?).