I'll have to think about the gooseneck, and how it changes things... a good thought... And I agree the elasticity of the mainsheet can help... but only to a point. If the mainsheet stretches enough to allow the boom to hit the shrouds, more problems can occur than are solved.
There is another really important piece of the puzzle, that someone else mentioned earlier in this discussion. The position of the traveler has a huge impact on the amount of damage that can happen in a gybe.
If the traveler is centered, and the boom is eased out only with the mainsheet, a gybe can be really dangerous. With that much mainsheet out, the boom can rise when it crosses, when the mainsail goose-wings around the mast. It can rise enough to actually hit the backstay as it comes across. If the boom was out touching (or very close to touching) the aft lower shroud, when it comes across it can impact the aft lower shroud on the other side. Both of these scenarios are potentially disastrous both to the boom--and the rig itself.
If the traveler is all the way over to the leeward side, then these problems can't happen, or at least are minimized, because the mainsheet is so much shorter, and the boom is stopped halfway across, before it can get really moving.
One of the things I really love about the Amel set up is that the traveler is long enough to actually be really useful as a sail trim tool. When sailing anything upwind of a beam reach, we adjust the traveler far more often than we do the mainsheet. If we are sailing downwind, the traveler is always (no exceptions--ever) eased down to the leeward side.
There are aways two parts to preventing damage in an accidental gybe. First is avoid the gybe in the first place. A nice idea, but it will happen to everybody. The second part is to be sure the boat is set up so damage is avoided or minimized.
Deltaville, VA, USA