The power down method gives the exact amount needed for curation. The curation fee is the is the biggest expense for most users.

It also eliminates the stress involved in trying to guess rewards for a post.

Comments are kind of problematic. In my case, the curation reward I recent for a comment (0.27 BP) covers the posting fee. If I am desperate to pay for a comments, I can just upvote the thing.

Thanks.