I have struggled for some time Steve to find a good Wurli sound from plugins - I finally settled on using the 2 together which I described above. Did a lot of experimenting with various settings - as I did with the Soundtoys Tremolator plugin which is on the Heritage Les Paul Gold Top slide guitar, the best plugin I have come across for that sound.
If I need to use a guitar amp (always hand-wired valve amps), then I use the very best of all for tremolo: Fulltone Supa-Trem 2 - as recommended by Bo Ramsey (I'm a fan!!). Cheers Steve, C