I agree.
I posted this before:
http://intl-ajpregu.physiology.org/c...ull/283/5/R993
I'm not sure if that's one of the same references you posted, it may be.
I also posted something on the kidneys which actually speaks to this a little and I think might add to it. I'll post it here if I can dig it up.
I personally like to get well hydrated around my workouts just to be sure, because sometimes I tend to be thirsty and ignore it. I am not always good about hydrating myself. I try to drink lots of water but I don't think for a second that there is any advantage whatsoever in me trying to down gallons of the stuff...or any other water containing beverage.
Edit* The link I posted is for the one you posted by Heinz. I'll leave it up in case someone wants to see it for themselves but it's the same thing.