I can do both vertical and horizontal shrugging motions with no pain. I can also do rowing movements with no pain, however, later in the evening I will feel my right trap start to tighten and then the next day it will be in pain and slowly get better over the course of 2 or 3 days.
If I let it get completely free of pain then give it two extra days, I can hammer traps with shrugs of any type and have no problem. If I throw in some light rowing, could be Chest Supported, Bent Over, Cable Rows, whatever, that trap is going to be in pain. I think I can do One Arm Rows without a problem but I haven't had a chance to conclusively verify it.
When it starts to tighten up heat seams to help a little. Rolling doesn't do a thing.