Hi Gaddwin.  We find that in some of the instances, the risk vs reward is just not worth it when boxing. Like some of the zones where you fall through cracks in the floor and die.  Why would I want to do this?   I am not familiar with the instance that you are referring to but I will try and share some of the tricks that I use. 

We box so many characters, but one of my favorite teams is a zerker, templar, assassin and 3 other "as needed" classes according to the challenge.  But I will focus on these 3 for this.

I got the Shield Ally AA on the templar and have them use a shield so they will block for me. With the AAs they have a 60% chance.  To do this they need to be standing near me facing the mob.  The Assassin needs to be standing behind the mob to back stab.  Sounds very annoying, but I use a mini macro  to rearrange them in combat so it happens with one click.

I leave them on follow, run a little past the mob till it turns towards me. Or shoot it and when it comes run a little past it until it turns around leaving its back to the assassin. Then I press my rearrange key. It does this:

• Tells the templar and assassin to follow me so they target and stick to me. 
• It then tells the templar to run forward 3 steps with <w#2@1>. With Combat auto face avatar on  in Options > Controls > View they will then turn to face the mob right beside me so they can block for me.
• It tells the Assassin to take 3 steps back so he can backstab properly.  <s#2@2>

If 0 was your follow macro in game then the whole macro for the Control Assistant would look something like: 

<0:1><w#2@1><s#2@2>

With this setup we get great DPS and are able to 6 box most X2 raid zones and have done all the city guild raids on level, not mentored.

In your group lineup, not to criticise, but I think you are a bit low on DPS. But you do have nice power regen