Your last paragraph is a little off. Dread Guard tank gear is extremely endurance heavy, with very little sacrifice in the mitigation stats. My shadow tank has 29k hp with 26% def., 65% shield, and 60% absorb. it's very easy to get over 27k with full mitigation stats, as long as some dread guard gear is in there.
Which is why you do not use a lot of DG as a sin tank. I RE most of what I get. learnt the robust 27B mods which is end heavy(56 end 34 absorb) and have replaced all the thrash from DG with it. looking to get the normal 27 robust so i can get 41 absorb and get my max mitigation gear as well.
I think your itemisation is not too good. My tank has 24.5k hp stimmed, 28% def, 69% shield 63% absorb. This is because the 3 DG pieces I got ive only used the armorings and maybe 1 enhancement. waiting for proper hazmat drops to get proper enhancements and mods.