I think John is offering a "new" solid state loop ( for an upcharge ) that has less bleed, is switchable between series and parallel, and works even better as an overall Master for the amp ....
But it's not stock, you have to request it ( I think ) ....
My PT-100 has the most updated FX loop I believe on it, there is a switch on the back that switches between Parallel / Serial. I have a minimix 2 that I don't use anymore because of it Not sure how it handles pedals, but I am running it with a G-system using a 4 cable method + a few pedals on the front end and it is quiet I'm using a hum-eliminator rack though to help with some hum, but it's the quietest I've gotten a amp running 4 cbl method.