chances are PVP wont be as affected by the delay as the instances are. the instances are running on less than optimized servers, they also have more graphics to load than a bare pvp arena does so it'll be less apparent for motion lag and timing issues. the skill lag will be the most noticeable of all the issues that create the overall problem.

needless to say people will be using sleep and stun so much during PVP lots of the lag issues will be lost in the "can't do anything" of those moves.