I didn't get to the point of IO's and I was slotting end reduc on all the toggles. I even got the badge that increases end. Still it was hard to go past a mob or two. I want to try the set again. I think after the rebirth I want to roll a dark/stone tank. But I will try to get theft of essence as soon as possible.
The TOE proc really was game-changing for DA, and it is not that hard to get. Do tip missions, reconfirm your morality, you get 50 merits. Run the first Signature Story arc, run the 2nd SSA, run one or the other again, you've got 3 Alignment merits. You can get the TOE proc and have one merit left over for the Performance Shifter proc. You can get the Miracle +recovery unique for 2 AMs too. Easy, easy to get, as is the Numina unique.
As far as putting END in your attacks, frankenslotting is a great way to do that. It doesn't cost much, and you don't have to wait till you are level 50. By level 25, you can make things a lot better.