In between disconnects/crashes and waiting through the queues, I hit the striking dummy at my house a few times and both DA AD and Grit-Souleater seemed to be doing 100% life steal, just like before.

In addition, doing Syphon Strike under Grit gives you back double the MP - that is, it gives you enough for a full Dark Arts in one hit.

(On the other hand, Shadowskin's animation getting downgraded to Rampart's turns the stomach just a little bit. Tear it down, revert the changes, un-release Stormblood Yoshi, etc.)