Since I have only PVPed in Azura since the Thieves Guild update I can only comment on that campaign. So far, we have not dealt with any lag issues at all but that campaign is also not maxed out with people. For those who haven't tried it yet, with all the lag in the other, you really should pop over and give it a try. It is a lot of fun for sure.
Why would i want to play on a server that has minimal population and i have to get completely new gear for? I'd rather play in slightly laggy conditions and have fights all the time than spend most of my time running around trying to find fights on the map.
Also in terms of the pvp the only thing i have to complain about are the spambushers and the spambards that are being used in this meta...the move speed i read somewhere that wasn't intended and it was being fixed...otherwise i really don't mind this pvp...ask me again next week when everyone is wearing their TG PVP gear