We tested that a little too, and it’s certainly relevant especially when you play with the grail ICE. If they make a foolish run, you can kill them (I did that with Merlin for the first time ever when his Gordian was in the bin) or set them back 3 turns by blowing up their rig.
If they play it safe, it slows them down a lot in the setting up stage. If they are counting on CC to get back SMX to save them from whatever, they’re in for a bad time. If they play it slow and steady, they risk the NEH player scoring. If they clot, well, they just used one of their now precious SMCs and I plan on making it difficult for you to get that clot back. It also puts a hurt on Lady tokens if you manage to get a couple Galahads out since Blacklist stops scavenge. Overall, it’s noticeably less good against Kate than it is vs Maxx but that’s because it’s fantastic against Maxx and it’s still super relevant vs Kate. Crim is the only matchup where it might not pull it’s weight but it does stop SOT Legworks and Siphons. At the very least it draws a card and invites the runner to waste a click on checking.