There is no port-replacement for 6 o'clock, as far as I know there's only grommet inserts for the bridge.
All grommets inserts are interesting on the tour, but then you find yourself asking, 'why do I have holes in my racquet now?'.
The best combo for me is ports at 12 and grommets at 3&9. Offers that wide-open, spinny package but tightens up the feel a bit.