Fights in groups, generally don't last long and unless the healer(s) is/are having trouble keeping up with the damage, I'll just fire off clara's and get on with the dps. If it resists, I don't try to make it stick, I just get on with it. Granted, if the group is having trouble killing stuff, I focus more on debuffing, but if there isn't a problem killing the stuff, dps is going to be far more important than debuffing.
Depending on the buffs you are getting in that group (at the very minimum, you should be gettting impetus), 800-1k should be easy even with legendary gear.
I usually hit zw in most group instances of around 1.4k (range is usually anywhere from 1.1k-2.2k). I do raid and have a few nice fabled pieces...I have been rather lucky in shard of hate...but there is very good group and quest gear available which should allow you to hit at least 1k.