That will never happen David because you religiously do your SMART Checks before every takeoff, checking Full & Free movement and in the correct sense
However (comma) there are some risks in having such a control on a switch that can be inadvertently knocked during flight. If control suddenly ceases, would going to (and finding) that switch be possible when watching the wayward model and probably waving the Tx over your head in true Retro style ??.
There is a glaring Murphy there and I can't imagine a need to vary the AUX settings during flight so, unless the Tx switch has the chosen pulse-length at all switch settings, Martin's trimpot pulser input starts to look more attractive from the Flight Safety aspects.