While I am not exactly sure how George's emulation circuits work... all the clips I've heard do sound good and it seems the Metroplex MKII owners are very happy with their amps..........
I do know a guy who has a Germino plexi and many Marshall's and he says he loves his Metrolpex MKII........
So it would seem as his innovative approach works at wrangling a cranked plexi and giving it a master volume and a loop. I guess until I play one side by side next to my 68 Metrokit NOS built plexi I am going to have to reserve judgement to be fair.