Amazingly enough it seems I have to reply to my own topic!
Anyway: I found a specialized Polyester repair company (outside the catamaran branch) able to repair on the spot (no transport required !!) and at a far better price. Hope to avoid total loss this way.
By the way: haven't stop sailing since. Ducktape performs miracles. Not even more water in hull than usually.
Hobie 16 = forever lasting it seems