Yeah servo failure is another good point.

Careful with the syncronizers though.

The Smartflyer posted above is interesting because it may be doing everthing digitally or discreetly in terms of generating the servo pulses. The trimmer seems to be used as a positition switch.

I have a cheaper servo adjuster, that has an on board crystal and POT.

I tried it once, then threw it away.

The crystal is subject to temperature changes, the POT is not very accurate ( and the carbon will wear under the sweep arm ) this means that you would have to adjust the syncronizer every time you go to fly... and after awhile you would have a hard time getting the two servos in perfect sync.

It was far more hassles than it was worth. I ended mixing the tail servos on the TX.