I would agree with Marcus' answer on this one.

Another question as an off-shoot from this one would be: What is the performance loss in checking each request against your htaccess rules?

If the answer is none, or very little, then perhaps keeping the 301 forever isn't a bad idea at all. You never know how long people will be linking towards those 301'd pages. I personally have some pages just like this which have been redirecting visitors for as many as 5 years, because it's better to keep the link juice than to end up as 404s.

An old answer to an old question, but one which has just helped me out tremendously. A true credit to the Q&A system!

I was under the impression that Open Graph data is completely separate from structured data, at least in the way Google is talking about.

There are quite a few examples of websites using both without any issue, for example:

http://www.telegraph.co.uk/culture/film/filmreviews/9257722/Dark-Shadows-review.html

This review features extensive Open Graph data, in addition to plenty of additional markup data, and this does not affect the rich snippets data which can be found by searching under the keywords "dark shadows review".