Of course it would be an easy decision if you could demo both but it is hard to find Moment skis in a demo fleet.
I personally have skied both and I own the PB&J. It has been a while since I skied them so I cant give the Volkls the proper credit cause its hard to remember all the nuances. From what I do remember they were stable at speed, solid in crud and so so in pow. They didnt blow me away or I would probably remember more about them. Seems like they had that typical GS tail found in most of the Volkl line up which I dont really care for. Sorry this review sucks but I have been on so many skis its hard to keep track.
The PB&J's are SICK. I wont go into too much detail because Blister already wrote the perfect review. So go check out the Blister Gear Review if you haven't already. As usual Blister is spot on! If I had to have a one ski quiver I'd pick the PB&J hands down. They do everything very well from POW to Park. They have about a 7/10 flex and charge through crud. Also, the guys at Moment are great and its good to support what they are doing. At your height and weight definitely go with the 188's.