Is PvP gear usefor for progression in PvE?

[magnanimousCynic]

Yes and no. The important thing to remember is PVP gear has ZERO accuracy. So make sure to replace it with gear that has accuracy as fast as possible. if you don't you'll have a hard time hitting things depending on your job. Another reason to replace them ASAP is that you basically can't meld the gear. The melds only work in PVP, but the melds don't work in PVP. It sounds stupid but it's a relic from how PVP used to work.

Weapons never have accuracy on them so you won't have to replace them until you get something with a higher ilvl.