They still benefit, but given the fact the sentries are not the greatest source of damage, its power has become much lower than before. On the contrary, rediced cost became much better for CA spamming.
+% Sentry Damage does still work, but since your main spenders are of the greatest damage, it's best to now roll Skill Damage on your quiver, for example, over to +%Cluster Arrow (or whatever main skill you are using).
And the thought process is to get your Hatred back as quickly as possible so you can continue to spam your cluster arrow as much as possible. With a decent enough setup, you're not going to be using your hatred spender that much and placing a polar station sentry strategically is not all that difficult once you get the hang of it.
There's some gameplay towards the end of the video in this one where I'm using EF > Focus, but generally it's a stick-and-move situation, so you're not depleting AS quickly. The strategy is effectively the same in Greater Rifts as well, even though you will undoubtedly find yourself out of hatred more often than in T6. http://youtu.be/jKEbDUU_TbE