Nope - not worth it for Pyro PVP. You would lose way too much Expertise, and, in turn, too much damage mitigation.
In fact, there's a lot of people running Pyro DPS that swear by using the old BM/Champ/Cent shells for the +15% RS Crit Chance bonus in PVE. Just slap in non-set PVE Armoring 27's and PVE Mod/Enhancement 27's. By being able to crit RS more often, it's a much larger DPS gain than a straight 8% damage buff. That's the intention, anyways.
ok cool was just wondering.
P.S: Love your vids, Malkiv!