Light Wind

I don't think its the hull shape which has much effect.  If you think about the centre of effort and the centre of resistance you'll suddenly realise that when you heel the boat you introduce quite an offset.  No wonder the boat heads up when heeled to leeward!  But in light winds that bit of weather-helm it produces can be an advantage and the increase in wavemaking resistance is slight.

If it's anything like round boards, which it undoubtedly is, it's about
balance.

Enough nose down to reduce the 'swirl' of the stern but not so much as to
introduce more wetted area of resistance than you have relieved yourself
of at the back works well.

Boats/Boards that are narrower at the nose introduce water line length
with reduced surface area which is why it works. Examples of boat that
are very difficult to do anything with in the light stuff like the L3000 with
it's flat grabby bottom and shallow stern rocker that even with the crew
sat right on the nose, it barely lifts the stern and heeling achieves not a
lot except to help the sail shape.

I should imagine that a merlin rocket would react well to the technique
described, it has a fine entry and rounded bottom, looks one hell of a
pointer, at least the one I saw did, do they vary from boat to boat, are
some 'clinker built' and others not, are their rigs 'open' in design/sail size
shape? Are they not 'river' boats, they must be good low wind performers.

I bet if it's a drifter they'll be heeling them, then at the very quietest
moment when everyone's concentrating their hardest, that guy with the
General Lee will hit the horn..

Whilst the rig rules are fairly open, they all have the same sail shape because that shape gives the most area within the allowable measurement limits.  So the sail shape is not really dictated by efficiency, but rather, by the rules.  They are very beautiful and well refined boats, but not cheap (or light).