So Canada is a bit more sensible than the FAA, which requires no cross country flying to qualify for becoming a gliding instructor! At least the Canadian authority has the sense to delegate to those who have some understanding of the art.
But I do think the tandem arrangement of the two seats in a training glider has advantages. No blind spots for the student, clear lookout both ways. And when he starts flying on his own, solo in the training machine, or in a single seat glider, it is both natural and familiar to be centered. A penalty in performance is paid by any twoseat arrangement side by side, just too broad to slide nicely through the air! Soaring a Falke? better find some pretty strong thermals! And keeping the engine running is CHEATING! that's not gliding! go on, man up, turn it off!
I did fly once with the old master himself, Derrick Piggot, in the Falke from Lasham.... he was very keen on motor glider training. He is still flying, had a check ride at our club this summer to fly his classic glider up the wire....our instructor was really on her mettle doing that check ride, you bet!
He's still supreme.