MP7 is not discontinued, the anniversary one apparently isn't either. Some folks think it is, I don't know why.
The body is made of fibre reinforced polymer. I will say it feels like the real one, however, the strength is not there. People have snap the receiver sling mounting point, best not to use that if you want to resale
There are quite a lot of variation amongst them
KSC Japan: Real engraved trade, meant for 134a, famous for nozzle breaking (~370fps on propane)
KSC Taiwan: Real engraved trade, meant for propane/green gas (400 fps on propane)
KWA/ Umarex: engraved trade with laser etching of Umarex's claim to H&K rights as well as 6mm bb marking and unique trademark. meant for propane/ green gas(400 fps on propane)
Umarex -German version: The same as KWA/Umarex except it is only semi auto
I had a MP7 before, pretty good SMG, it's way too heavy for a backup imho. Range is too poor for primary (except maybe CQB game with <80ft engagement distance)
As for VFC suppressor, VFC aka Umarex one was specifically design for it.