The only way I can tell of my DPS is any good now is if I can steal aggro from a solid tank.
This "test" does not work. Imbues still aren't effected by -threat and it's not pure total damage to steal; if a single hit is "big enough" you can flip something even if you're the lowest total damage dealer. I suspect other factors, too, but they're hard and tedious to test; eg. low defenses, distance, level, lack of movement, etc..
As an example, I have a couple ranged. One is a grade-A thrower that auto-attacks around 10~12k per hit. One is a repurposed HC 1st life INQ with autos in the 2~3K'ish range. Both have -80 ranged threat. The INQ will rip it right off a tank and it's doing about HALF the total auto-attack damage of the thrower. The Big-D thrower is about 5~10% imbue. The INQ is about 80~90% imbue.
As another test/comparison between the two (cuz I was curious), my thrower can solo kill Zulkis (after Irk) before the raid finishes killing either Rudus or Gish. My INQ trying the same trick can't kill Zulkis before the raid finishes both Rudus and Gish and turns to Zulkis.
Basically, just ignore agro-rips. They're nearly meaningless unless you have Defense enabled. The +threat from that is enough to rip it from almost anyone even with ultra-low damage.