when mixed with a gas turbine engines slower spool up time
For a turbofan, certainly.
But SOP on the PT6-powered aircraft that I have encountered is to use the prop levers to set the prop (and the corresponding engine) RPM on final approach,so that the need to spool up the engine core didn't arise - 1675 PRPM rings a bell on the Shorts 360, for example.
I have no experience of the Twotter, but of course that has PT6s too.