>If you had you'll notice it has a tailwheel and a three position prop, both of which require a PPL to do differences training to use<
Just for the record, the Vigilant does not have a true VP propeller; it has a three-position fixed-pitch prop, of which one position is feathered. Differences training is certainly required for someone from a Vigilant background converting on to an SEP aircraft with a VP propeller.
I also wouldn't sign anyone off for tailwheel differences training on the basis of having flown a Vigilant since the takeoff technique is not representative of a true taildragger.