Bill,
the statistics covers accidents and launches in the period from
2002-2008. Brought to an annualized figure that means there were an
average of 1,449,500 glider launches every year for the period. That
is, the analysis covers about 10,146,500 launches of all types in
Germany and the accidents that resulted from these. That's a pretty
big sample. The sample also covers 60 winches in France, listed
separately. (the only accidents in France involved electric winces)

In Germany, for the period (2002-2008), there was a yearly average of:
712,500 - Winch Launches
237,000 - Aero tows
500,000 - Motorglider take offs (fixed position motors)

The number of motorized glider take offs is not indicated, but the
number of their accidents is, which comes out to 5.3% of all glider
launch accidents involves this type of launch.

I don't think the sample is too small.

Your statement that one could simply install an AOA indicator to allow
the pilot to avoid exceeding the AOA misses the point entirely. The
point is that exceeding the AOA occurs because of what the winch does,
not the pilot - namely, excessive initial launch speed/tension/power
resulting in an uncontrollable excessive initial pitch up movement
that ends with a stall and flip into the ground at high speed within
seconds.

The only aircraft type pattern mentioned is that involving GROBs.
These types were never involved in flip ins during inititial launch.
Another anomaly is that in 45% of all accidents involving broken weak
links Grobs were involved - indicating the certified strength of the
weak links for Grobs are not strong enough.

I think the analysis is very thorough and makes strong
recommendations. What you are doing, strong initial acceleration
launches (which I presume exceed 1g rope tension), is what they are
saying should be avoided. Later in the launch phase, it's OK to
increase tension beyond 1g, but not in the initial danger zone.