In what content are they a burden? You could literally clear Ravex/Bisex/Alexander with any combination as long as you have atleast one healer and tank. You could run with 7 DRK and a SCH if you wanted. Dosent matter.
If you think being a burden is doing 200 less max damage compared to a melee (or 50-100 compared to a caster) then oh.. boo hoo?
