The more I think about it, the more I wonder if the cable in the old school manual trim was actually a push pull type. It may have been actuating a big screw that was attached to the trim ring, thus running the nozzle up and down. That's how the electric VTS works. The motor turns a big screw that actuates a rod attached to a captive nut that runs in a channel. I don't think a push pull cable can handle the up and down force that's applied to the nozzle.
The trim like the old HX works but having to get off the ski to change the trim is a bit of a pain.