I love my GII Hunter as well. I threaded my barrel at the factory length as well. I installed a Syrac adjustable gas block. I have mine topped with a Bushy HDMR (3.5x21) with the TREMOR2 reticle. I'm practicing for local DMR matches. Mine has run flawlessly as well. Accuracy out to 700yds has been great. I would share group sizes, but I'm banging metal, not punching holes in paper. My local range goes out to ~1200. I have stayed below 700 so far. Over the next month I'll start to stretch further out.
My next step is to look into getting a GII stripped upper from DPMS and installing a barrel kit from JP in 6.5 Creedmoor. Need to look into whether all of these parts would work together.