i used @bellyrub once with a little amount so of course there wan't much if a change when it came down to attention
and I'm still trying @minnowbooster these days, which so far gave me some little financial reward but here again i don't think I got much exposure Especially since I used them a few days after I posted my article, to avoid to have those spam-looking comments.
I also read recently they have changed their reward system so their up vote will be worth less, but you might could get more exposure, which I still kinda doubt. as you said, it might only make sense if you put in a lot of your own SBD first..
check out this post where they explain about it themselves
Thanks, @maxinpower for sharing this article.
I will. check it out.