This was one of the first major IO purchases for my Kin def, but I specced out of it and stuck it in my own stamina instead. The end grant was almost always unnoticeable (I also slot 3 EndMod in SB already!), and it didn't trigger on post-nuke/crash players enough to make a difference. Either a well-placed transference, or just a blue candy was the real solution. From a performance perspective, I do NOT recommend this slotting.
Of course, then I made a small fortune on the markets, and I recently bought another Perf Shifter +Endurance to put into SB. Now I get it, and so do my teammates!