It's not about the complexity of the aircraft, it's entirely about the
quality of the instruction.

We do about 4000-5000 tuition flights a year, mostly on ASK-21s. About half
of them are ab initio. No matter how well we train people (and I'd like to
think our instructors'experience and skills are above average), we find
that there's always a time when early solo pilots (who also fly their first
solo's on the twoseaters) need just that extra safety margin. A margin that
a glider like the ASK-21 offers. And a Janus C doesn't. Keeps the student
pilot and the glider in one piece (in that order).

CAN you use a Janus C for ab initio. Sure. Would I like my club to do so?
No way. There's aircraft far better suited for that, from both a
maintenance and safety point of view. Just my two cents.