I like mine a lot. I had one with a 16 inch barrel and sold it to get the one with the longer barrel. The previous one didn't like ammo with the tar sealant like the south African ammo. Also didn't cycle properly with some German because they were underpowered. It worked great with Winchester, Privi, Wolf, Radway Green (surplus). I have also used the fully auto G3 and HK11 in the past. Personaly I like the recoil as is. They also sell rails for it and claw mounts if you want to scope it. The rails I would go for those B&T style mounts or an actual B&T mount ($200) or cheaper than dirt stocks the Hensoldt scope with the mount from time time. If you want to go the acog road then get a trijicon mount. But then you get an optic that is as much as the rifle.
Accuracy has been good for me. I don't use it for matches or anything. A member here is selling one for $1,200 if you are a green member. The price is really good in my opinion. Also Four Seasons in Woburn sells them at a great price.
http://www.northeastshooters.com/vbulletin/threads/113331-WTS-PTR-91-with-Magpul-Stock-in-MA
Anyway good luck with your decision. People either like them a lot or can't stand them.