Welcome, Frolo. Good to have another boxer on board. I recommend adding a 6th as soon as you can. With the dirge, any Melee dps will fill out the 6th slot nicely.

SK makes a great Caster Group Tank, especially if he's grouped with an Illy & Troubadour. at lvl 59 with 110+ AA's, my SK can hold aggro against anything my casters can cast. I had my doubts at first, but i'm satisfied now. If you want to be a Defensive Tank, go Zerker and run a Dirge. If you want to be an Offensive tank, go SK and run a Troub. If you want to be The Tank, run a Guardian.

I've suggested this before and I will again... Forget about levels. Turn off Combat XP at lvl 10 and only gain XP through Quests until you hit lvl 70. As a 4-box or higher, you should be able to hit all the content up to lvl 70 with relative ease, even if you have to green-out/out-level the dungeon first. the right AA's can change the dynamics of the entire group. I did this on my current group and still had to skip content. I'm already pondering replacing the SK with a Zerker (once the rest of the team is lvl 80), so I can go back and finish all those quests I missed... then retire the zerker at level 50 and use him to mentor down TSO Dungeons to make shard gathering simple 8o

I recently put my dps team into Heritage quest mode. I just finished all the heritage quests up to lvl 40 last night (the team is lvl 59). Each heritage quest is 'almost' one AA Point and great status for your Guild. Some are easy, some are hard, but they're all worth it. You also won't get better equipment for 10-15 levels than the heritage item. AND, being a boxer makes Heritage quests Simple, since you always have a full group that needs all the updates. I recommend doing each heritage quest at the level it's available, since you're generally taking down lots of named mobs that give great AA XP. Going back and doing the quests when theyr'e grey denies you all that tasty AA XP from mob kills and treasure loots.

To echo Shdwdrgn and in the immortal voice of the Deadites: Join Us (on Oasis).

g'luck