I'm a huge fan of only using FB for retargeting. You know you aren't targeting spammers, and there's some sort of legitimate interest there. The only risk here

I'm a huge fan of only using FB for retargeting. You know you aren't targeting spammers, and there's some sort of legitimate interest there. The only risk here is some cannibalization and duplication, but if you use some higher end analytics and pay attention to it that shouldn't be too much of an issue.