No, it cuts your base damage in half. With +25% fortification reduction that means that anyone who's bonus from criticals and sneak attack damage is more than 4x the base damage of their attacks, which is going to be true even for STR based rogues, Precision is a pretty large DPS increase.
But that said.... we are still talking about Sneak in PvP. I mean, even if stealth was functional it still wouldn't give you any sneak attack damage or anything like that except on your first swing. In order for that to work they have to not be targeting you. Seems like a lot of to-do about nothing.