Having watched the online tutorial on this I'm still unclear as to what advantage this presents over more "traditional techniques e.g. Chipping medium/HS. Thoughts and opinions welcomed.

I haven't used it myself but seems that the advantage is that you save one step, no need for chipping fluid or hairspray between the base and top coat.
Just paint top and scratch as desired.

Exactly ,I try with the MMP paints and work pretty well

Thanks for you responses guys. I think I might give it a go...