I personally wouldn't want someone asking me to do that. If someone likes your review enough, they will vote it up. And if one of us likes it enough, we'll merit it
The fact is, if you don't have a merit worthy comment, you will not get a merit for it no matter if it is up voted or not. I would leave it up to other peoples discretion, instead of asking them to. If you have a good review, you shouldn't have to ask someone to do that.