RE: Your 2 Cent Vote is Worthless, The Real Deal on Dust Votes
I can't comment about the maths but I suspected as much a while ago but never looked into it until @timcliff's post. I still don't know the math but this makes sense to me:
If your voting power doesn't allow for a 0.03 vote on a comment Don't Waste Your Vote! Instead save your votes and only upvote actual posts.
If your voting power allows for a 0.03 vote on comments make sure to use this as your cut off. Giving a 1 or 2 cent upvote on a comment is a waste of your voting power and isn't giving a reward to the author as you intended.