From what I understand, all early PTR rifles had match bbls, the manufacturer figured he was building a high end rifle and people would want to use high quality ammo. They soon found out their customers wanted it to shoot surplus ammo too, so a lot were returned when they puked on 3rd world surplus and were rebarreled or rechambered to looser specs. After that, their standard rifle was sold with the more reliable specs. Haven't really looked into them currently, but I suspect they sell them with both types of bbls depending on model.
The factory collapsable stock is a pain to actually shoot for most people, the buttplate is curved the wrong way! The newer sidefolder ones that look like the one on the MP5PDW are a lot more comfortable.
Depending on how yours shoots, I would use a claw mount if the accuracy wasn't Sniper grade. If it is an exceptional shooter, you might want to look into getting a picatinny rail welded directly to the receiver, add the receiver stiffener rails (can't use the collapsable stock with them though) and get a trigger job done.
If you reload, the rubber port buffer is a nice addition.