The change in Yomi was actually not that significant - it was a smallish price drop for their demonic troops. Good, but hardly far enough.
I suffered very, very badly from banishments against Mictlan, though I ended up winning that war anyway by using mass bakemono archers and hannya - both nifty units, but again, not gamebreakers. In a fair fight indy archers work as well as bakemono, though they're not stealthy; and massed bakemono are counterable by the same tactics that work against any other massed ranged unit. All oni are vulnerable in melee thanks to their piss-poor armour, and Yomi is far from the only nation that can easily stomp indies with skilfully used nations. Their national spells are too high-level to be THAT useful (by then you can field the excellent dai-oni SCs), and End of Culture would also negate oni mages.
I actually saw an excellent post on another forum on Yomi's weaknesses; I'm asking for the author's permission to quote it.
