Personally, I run a pretty common team. 84 Warrior, 83 Ranger, 83 Cleric, 83 Enchanter, 83 Beastlord, and 83 Druid. I have a tank, puller/damage, healer, CC/damage, damager/pet damage/beasty goodness, and evac/back up heal/nuker. I have every corner covered.
When I see your team, I see 2 tanks and a puller. I imagine you probably have a cleric merc and 2 caster mercs. Personally, I think you need some crowd control. I would personally do a Bard or Mage. Don't get me wrong, I love my beastlord but I think your team needs a different approach. A bard can single pull and mez if things go south with the ranger. However, a mage's pet can off tank in the high end game. Maybe my beastlord is not appropriate geared or I'm lacking loads of pet AAs but my ranger can tank better than my beastlord's pet.
Here are some group set ups for you:
Bard, Warrior, SK, Ranger, Cleric Merc, Caster Merc.
or
Mage w/ pet, Warrior, SK, Ranger, Cleric Merc, and Caster Merc.
In the long run, its your decision but those are my suggestions.