At the time the first smoke units were introduced, Triang trains were definitely aimed at the toy market, and still were when the Synchrosmoke units came along. They just added to the play value of these toys. By the time the 4-4-0 units appeared (which was quite a few years after Synchrosmoke was discontinued, inevitably due to costs), Hornby were aiming a little higher, and these units worked quite well and were obviously cheaper than of old. As with many things, these were all "of their time". At least they can be disconnected if not required.