Lexur - 5:01 am on Sep 3, 2013 (gmt 0)
It's not relevant if you're the owner of the website. There is a lot of guest bloggers who post in anyone's blog just to have a link to their G+ profile.
Keep in mind, it's not only a question of URL but of the rel attribute. I suspect Google gives more credit to a link with the atribute publisher than other without it when is trying to check the page publisher. Sound logical, isnt?
Regarding the kind of URL, I think both are valid. Just add one of it and look if your G+ page shows a checkmark as verified page; mine does it.