I have both of these classes at 70, my lock is all pvp geared, my hunter all pve. I've done quite a few arena's with my lock, and hunters burst is a major pain in the ass for a lock. Even then though, the longer the lock stays alive the more likely the hunters gonna die 1v1 due to dots. Same gear, same skill and same hps a lock has alot more going for it in order to survive, healthstone, sacrificed void, siphon life, drain life, soul link etc. A hunter can burst a lock down if they get the jump, but if not they are toast. Nagrand arena hunters will own a lock unless the lock starts kiting around pillars, and the other arena's favor the lock also due to los. As far as bgs go, all of them favor hunters due to the wide open spaces. World pvp is dependent on the terrain, but usually it will favor the hunter.

One major advantage a lock has in the dps department is the dot and kite tactic, they don't actively have to do anything while their dots tick down, while a hunter needs to maintian los, and the target has to be in front of them. Locks can instacast 3 dots if specced right that don't require the mob to be in front, only in range and not behind an object or barrier. I'm currently 3 boxing a lock and 2 shadow priests, and have messed around with 3 locks also, and i'd think the los issue would make locks alot easier to mb. If your looking to do a 5man crew, 4 locks and a shadow priest will be tons of fun, and so would a 5 hunter or 4 hunter 1 shaman (self rez, totems, heals etc) team.