Since we are running in an actor whose logic is completely shielded from the "user space" it's not that easy to have the user provide us with custom logic. Also, we can't really use actor messages either since they must be fully serializable.
So, I'd vote against a custom redirect strategy. If the user has special requirements they can implement their custom redirection logic on "their side of the fence".

In total I think we should implement this logic:

1. For GET or HEAD requests we follow redirects in 301, 302, 303 and 307 responses.
2. For non-GET/HEAD requests we follow redirects in 303 responses and change the request method to GET.
3. For all other cases we don't follow the redirect but return the response as is.

Does this make sense?