I can't really comment on lv60 zerkers, but for what it's worth me and a member of my guild did a few duels for fun at lv32 (Slayer[me] vs Berserker [him]) and it was ridiculously easy to win.
Did he use the increased movement speed ability? Use it too and run in circles while he charges.
Is he close with his charged attack? Dash away.
Do I need MP? Run up in his face and hit him 3 times before he hits me once because he can't use any of his strong attacks without MP.
Is his health low? Ranged attack.
So far it looks like Berserkers suck in 1v1.
in 1v1 zerkers will suck all the way to 55, then they catch up and end up being just average
in group play they are excellent all the way to cap
Haven't gotten to sixty but I've seen videos of 60 berserkers. They get a good bit faster with flurry of blows and all the attack speed glyphs you can get. They get their dodge ability at 60 so if figure if used correctly could really make 1v1's a lot easier against other melee. Best combo for a zerker is a healer. They work incredibly well together. You can essentially be a mobile bunker for the healer because people refuse to get near you and the healer can just keep you up. If you get glyph of the mind spark for block that gets you quite a bit of mana back, especially against lancers.
The trick with zerker in 1v1 is to not charge up your abilities a lot unless you know for sure that you are going to get a solid hit. Half the reason people get frustrated( and I did for awhile) when they first play berserker in PvP is that they Charge up a big attack which is like 100 mana per charge and then they get hit and all of its gone, or they miss because the enemy could easily see it coming. Use your abilities quickly. just spam thunder strike as a regular hit a bunch. use WW as just a one or two charge when they get in close. Make sure you aim your strikes very well. You get better and better at it....
PvP has zero balance at max level. All you have is nukes and heals plus a lancer for pulls. If you are in this for the balanced PvP you are going to be extremely disapointed when you hit max level in less than a week and the PvP is just a roaming pack of nukes with a lancer pulling food.
Zerker and Warrior are useless in PvP at max level. All that matters is healing the lancer and nukeing from range. Slayers are only usefull because they can build to a massive 1shot strike on whatever the lancer pulls.