User blog comment:Rappy 4187/Guide to Infoboxes/@comment-166269-20130116005658/@comment-957747-20130116175938

All excellent points. I personally disagree with your first point, but then again, this is simply my user preference. IMO, using HTML overly complicates the process. IYO, the opposite does. :)

IDs can be useful over class if you know there should only ever be one on a page. Furthermore, if you're adding styling with IDs and there's more than one, it still works. The only real thing that breaks is any JS that should operate on those IDs (it will only select the last on the page).