Don't chew up your bolts/nuts with a VGrip, they might rust if the coating is abraded, then you have ghetto. Put a box end or a little crescent on there and socket the other side, make sure your crescent is tight or the box end fits, or you'll round your bolt/nut and it may rust as before. Tap with wood dowel, or brass punch to advance the bolt as you loosen, so there's space. Watch your frame paint around tools.
No VGrip has ever touched my bike, They are a great tool, but they are for taking old rusted out bolts out of fence posts and winding out headless wood screws and stuff. Things you don't mind defacing/destroying in the process of removal. They are an effective demolition tool, and great for holding things in place and stuff, but where fine/aesthetic machinery is concerned, you are "getting medieval" if you use them. Put 'em away; right tool for the right job ;-)
I found a super clever hybrid crescent/vgrip thingy which works great, and can hold a nut like a catcher's cup guard. I think "Home Cheapo" would have one.