I hunted with 170's for years and took a lot of deer in that time, the 170's will kill just fine, but... I switched to 150's a couple years ago, and have taken enough deer in that time to feel that the 150's seem to drop deer a little faster.
This is important to me as most of my hunting now, is from a tree stand in the afternoon/eves. I greatly appreciate not having as interesting tracking jobs as it's getting dark. Not that the deer arn't dead, just like finding them without a flashlight.
I'm still getting pass throughs, and adequate blood trails and meat damage is no worse than before, I won't be switching back to 170's any time soon.
At present I'm using Win. 150Power points, but I'm sure Rem. 150 corelokts would do as well. That's my experiance, been at this for 36 years now.