a restart would be useful of course, but you'd greatly benefit from taking a bit of time to re-look at some of the things we've discussed, do further testing and really review the current setup.
i'll give my opinion on a few pointers, we'll begin with droprates..
it began at 15x and 1% droprate (15:1), then went to 30x and 2% droprate (15:1). In my opinion the current ratio is too low anyway, and really ought to be somewhere in the range of 30x with 30% droprate. that may sound a lot compared to your current ratio but let's use a very crude example, an up and coming dk kills 500 elite yeti's (
http://www.guiamuonline.com/devias-drop-normal). 30% * 500 = 150 item drops. of the 22 "normal" item categories a yeti has, 3 are armour parts that DK can use. so 150*(3/22) = ~20 dk armor items from 500 kills, enough chance for a handful with +opt to be worthwhile. after those 500 kills the dk would certainly want to move on and will likely be level sufficient to do so as well.