Two quick comments on this discussion:

1. There's a timing difference between the main wing and the tail.
Entering lift there is a transition region where the lift is growing
stronger as the glider moves forward. The main wing will be about 15
feet ahead of the tail. As a result the main wing will be at a higher
angle of attack than the tail during the transition into the lift,
creating a pitch-up tendency until the aircraft has gone through the
transition region. This would tend to offset the pitch-down tendency
that's been discussed. I've personally flown aircraft that pitched
down, others that pitched up. Flex-wing hang gliders tend to pitch up
very strongly on entering lift. However, I used to fly a rigid-wing
hang glider (flying wing) that pitched down. I never could explain
the difference.

2. There's been a few mentions of the download on the tail, and Martin
referred to an upload on the tail of a model but said this was
"probably unsuitable for a manned plane." Not at all: at thermaling
speeds, manned sailplanes have a substantial upload on the tail
(contrary to everything my instructors told me!). This was a topic of
discussion some months ago on RAS. Since Martin is familiar with
doing this in models, it may surprise him rather less than it did me -
but I ran the numbers and, indeed, it is so!