both work wonders.. i personally have used pro grip & grip ease because i didn't get that glue stain as with bikini bite.. it is not so much a stain, but the can make the suit darker in certain places and if you are using a bright color like red or yellow, then ya really gotta be careful with applications!!!
to apply, i didn't even put it directly on my suit, i put it on my ass and then rubbed my suit down on top of the glue on my ass.. it seemed to work better and i didn't get that wet stain look. Just make sure the strings attaching the suit bottom to the top are pulled tight first and everything is in place, then just move the suit a little, glue it down and rub out the ripples.