While I liked having my MB-16 on my N80, I LOVED having the MB-15 on my F100. But now I'm wondering if the additional sensor control/joystick, vertical shutter relase and command/subcommand dials are worth the additional weight. It gets heavy, even with my Nikonians Pro Strap and Sling Strap.
My lenses aren't "pro" f/2.8 either...typically, I'm with a 28-105 which is probably on there the most; it certainly weighs more than the 28-200G that I have. And my old 70-300D ED isn't that heavy either.
I typically have the Kirk L-bracket installed, too. I doubt taking it off would reduce much. I've pretty much had the grip on since I got the camera a little over a year ago.
I just might try it without the grip. (I've only once come close to discharging the battery and never touched the spare (in the body).