From my experience, JML Lead is fine against Rey and Kylo, but struggle against JKR lead+JML (it's all about "will opponent's JKR, which go first thanks to Tenacity up, mark my JKR ?").
The best solution I've found so far is to switch to JKR lead to win mirror, even without Wat.
I do agree it's kind of disappointing, because ultimate isn't used in this case. Imo, it's not really a "JML isn't strong enough" situation but more a "JML is frustating because you can't use his full potential (lead+ultimate) if you want to use him at full potential, as a member of a JKR team" case.
