Not sure I'd agree with your thinking on the marketing of the
sustainer and the self-launch glider (ignoring the Ultralights;
incidentally the Silent Electro is an ultralight in Europe).

As a long time owner of several self-launch sailplanes I'd say
self launch buyers and sustainer buyers tend to have different
priorities. Self launchers are heavier, costlier and more
complex: unless you do a lot of flying (say 200 hours per
year) their real running costs are more than a conventional
sailplane. Plus their glide performance, especially in weak
conditions, is worse: this is a real drawback. And when they
breakdown the costs can be truly fantastic: look up the cost of
rebuilding a Solo or rotary engine or, worse, buying a new
engine. Against this is the hard to quantify "independence" and
the ability to get home (usually). Remember all self-launch
owners are complete masters of that branch of accounting
known as "man maths".

Sustainer owners and buyers are a much saner bunch; lower
costs, lighter weight, minor (or nil) performance loss and you
still get home (usually). Not sure many go from sustainer to
self launch? I can see self launch owners going to FES though.
Dave Walsh