Yes, I do have him activated. I wish he and the Datacron got the kind of holds you are seeing!
Not sure what the point about the abilities is- thats just power creep, each new GL (and sometimes non-GLs) will have better abilities than the last so people get them, particularly those who spend.
GLAT is fine, performs well as long as you have an Ezra that stays alive. Mine was getting punished as he was at R7 and the rest of my GLAT team at the unlock levels, I improved their relic levels and its much better for holds. Thats just the world of relic delta- others invested better in their GLAT team to reflect how RD works, and I didnt so fair play. If you're running her without Ezra then its to be expected that she won't be great. So essentially others did it better than me, Its why posts like yours get me going, they never consider that the other player was better than them, or the teams they were going in with were less than optimum.
Anyway regarding the SLKR counter- it really helps if your SLKR is R9 minumum (or at least matches their PKHO team), in 3s Stun Bane and pretty much auto. In 5s, its honestly hard to lose as you have your full FO team that gets SLKR going quicker to Ultimate.