Since F-class does not permit mag feed, only single shot (but you can still use a mag-fed rifle as a single-shot) the issue is moot. Depends on what sort of 1000 yard competition.
If you asked me what I thought of 6X47L a month ago, I'd have told you to save your money. Having just discovered what that round can do with Vihtavuori N560, I can tell you it is a phenomenal cartridge!!!
SO Mark, have you bought yourself a Grady White yet???