I've always used sk=lf to get chronological Facebook. I wonder what the difference is, if any because I'm trying h_chr and it seems to be the same order.

My issue with it has been even though it's chronological, it doesn't actually show you all the posts from all your friends. It still does it's own crappy algorithmic filter(I think it's based on interaction) and I miss stuff from people I want to hear from all the time. I only have about 60 friends and no one is relatively chatty so there's no reason why I should miss anything.