Complaint doesn't really expedite your case, but instead tells you if your case is now out of ESC or not.
Once you've know its out of ESC then you can go to DIBP with confidence, which will result in your case getting processed quicker.
Well I agree, if one has waited for so many months a couple of more weeks won't really hurt. However, if you submitted your docs in early Jan 2014 I expect your ESC to be over by now.
In any case good luck :) keep us informed.