I don't get this. I have almost half his dps, mainly glass cannon, but I play not that differently from what he's doing which is dodging shots and dps'ing. Like Ferrio said, you're basically trading one Discipline skill for another (SS to SP). My crowd control is much better and I use tactical advantage to set up positions so I have longer intervals between dps and running. But other than that, what's the big deal? He still dies from those annoying spears if he doesn't SP in time which is the same for me.
Running an all res DH gives you way more leeway. He can take two-three hits from spearman, and he can also take one hit from some melee mobs, and one mortar from all champion packs. His CC is the exact same as yours too, he runs Displacement on Smoke Screen and he still runs Caltrops.