Just as a side note, i've got Oxford Sports grips fitted to my FZS600 and I fitted directly to the battery.
So far i've left them on twice and although they flatten the battery enough to prevent the bike starting, they don't go on and completely kill it. They're designed (as mentioned) to turn off when the voltage reaches a certain low level purely to save irreversable damage to the battery....still a fricking nightmare when you do it though!....lucky i'm good and sprinting and bump starting!
My mate has them fitted to the battery but he's never left them on the git. Think my problem is that my FZ1 heated grips ARE wired to a switch so i'm used to not having to think about it.
The Oxford grips work well though, not needed 100% power yet but then i've combined them with winter muffs....it's like 2 toastie oven mitts to keep your hands in
Err.....isn't fitting them in Spring kind of the wrong time lol