Ocean Air has never had a retaining pin - or hydraulics, you just wind up the keel and leave it there. If I remember rightly Godfrey said once that his hydraulics leaked (or crept?) a bit , so he had to pump the keel up slightly before he could get the pin out. I suppose this would be a good reason for not putting the pin as high as it will possibly go.
When Ocean Air takes the ground the keel is pushed about 8" up to the top of the case and she sits down bolt upright. She has been doing this for 10 years now and it doesn't seem to cause any problem. I think that the centre of gravity issue doesn't matter a lot as the keel bulb is always under the hull and that is the heaviest bit. Boats like Foxterriers and E boats have no bulb, can lift their keels completely flush with the bottom and they seem to survive! - don't steer too well with no keel at all tho.