I would usually never hire such an expensive model, either, but I tried it last week, and it went so well that my opponent forfeit at the end of turn 2.
My crew was:
Asami w/ 6 stones
Amanjaku
McCabe
Luna
Jorogumo w/ Masked Agent
Ama No Zako
Tengu
Wedge deployment and Turf War.
I played very aggressively, and got my hired Jorogumo and a summoned Jorogumo right into my opponent's face, and McCabe tossed a saber to the first Jorogumo, which then got fast and ignored HtW/HtK/armor/shielded, and gave itself + flips with flicker, so of course it got 1 or 2 kills and removed flicker. Then it quick actioned to toss the saber to the next Jorogumo, which also killed more than 1 model. McCabe and the tengu claimed turf war markers, and Asami supported the Jorogumo, and Ama No Zako also got into the fray. At the end of turn 2 more than half his crew had died, and there was no way he would've survived a turn 3.
I think hiring a second master is usually not optimal, but McCabe brings so much versatility and support to Asami's crew, and she can summon models to make up for the low model count that a second master causes. Maybe my next game with this crew won't go as well, but McCabe will always be on my mind with Asami because of how brutally efficient he made those Jorogumo.
Having said that, the Oni keyword and Versatile Ten Thunders models provide enough variety and fun that a second master certainly isn't necessary. And maybe my game would have been just as one sided without McCabe and with a Samurai and Dawn Serpent instead? It's hard to say.