It's definitely been tested before. But not recently. The last test I'm aware of is when, I think it was Byrth, tested it after the change to it's ftp properties. This was the change that made it generate more enmity depending on TP.
While I think retesting is a good idea I don't think there are any significant discoveries hiding in there.
Even with the Augment, based on what we know right now, it's not going to suddenly make atonement useful. The base damage is just far far too low to compete with the enmity generated by DD WS. Even if we went on the low end and said Atonement vs a 20k WS, with Atonement doing around 2k~ the enmity mod would have to be x10 to even get in the same vicinity.
It probably would have been more useful if they'd just changed Atonement to a static enmity value like enmity spells and such. Then you could dump all the WSD+ and go full enmity+.
They really need to update Atonement. Back at 75 it was amazing. Decent dmg, and was the best enmity generation you could get. And you were helping kill the mob while keeping hate. But while DD WS have scaled up into the tens of thousands of dmg, atonement's update put it up to... 2k~. And that's with Burt and lots of WSD gear. -_-
Anyway. I'm not sure if I'm feeling up to retesting Atonement myself. These sorts of enmity tests are a real pain in the ***. But I'll think about it at least.