Camped the Unyielding Devoution Bow for my Ranger on my 3box. Most Devout Sentry is a majorly Devout pain-in-the-buttocks.
He casts a guard on himself that eats up spell and melee dmg alike (including damage shields). You can tell when he has cast because your DPS crawls to a halt on him. I had no luck trying to dispell it off him. Bring DPS.
Took 5 nights camping him around 6 hours per session. Most nights I was lucky to see him 2-3 times, one night I did get him to pop about once an hour. That was clearing all his PHers in a timely fashion before repops.
There are four PH'ers. 2x static on the North side of the area in front of the bridge/gate (one infront of a tent, one in an alcove/cave with a buddy). 1x that roams under the bridge/gate. 1x static under the bridge/gate structure on the northern side. Ph'ers all have the same name "a devout goblin sentry".
2 of the 3 static PHers have a buddy that will aggro when you pull them (they aren't tethered or anything - just proximity aggro) like most of the static mobs in the area. The roamer is easy to get single. So bring CC or just burn down 2 at a time like I did. Once you break the camp and split up the aggro-linked spawns the place is pretty easy to lock down.
There is a safe spot to camp if you shrink your team down and thats just around the corner from the two goblins spit roasting some meat on the north side near the gate/bridge.. Wedge yourself in between the mining-cart and the wall around the corner from them and you are good to go.
Bow is very rare drop in my experience. On the upside the Devout Sentry when he did show was most generous with T2 armor - including a double drop of BPs Trash can all drop random stat/purity augs and the XP is not bad at all if you are chain pulling the area and keeping it clean. Good luck to any mates/guildees wanting to run down and loot rot-drops ... unless they are Rogues or half decent floppers.
Zone is not friendly - lots of see-invis roamers and not many safe placed to set up camp. First night there I spent a lot of time on my rogue dragging/rezzing 3-boxers from other camps that were getting hammered by the odd see-invis roamer that would aggro nearby mobs in on them.
... for a grouper, the bow under Pureshot /disc on a burn is truely some canned sickness. :o)