I've read and commented on so many of these HF posts, that I can't point out where I could find a linkable one. But I'm pretty sure if you just read all the comments on this one post you'll find someone correcting me on the 15SP vs 5SP point. I know I started calculating based on 15SP, which is what I started with 7 months ago, and was corrected several times, including by someone speaking for himself about one of his accounts.