I've really really tried, but I really dislike the jaguar, especially for Warlords Monty.
Jag rushing has such a small window, and can be stopped dead cold by a single axeman. In exchange, you're accepting a remarkably crippled version of a unit that should be extremely useful for your civ.
It works if you're exploiting the default AI that just sits archers in its cities, but against BetterAI or human opponents, they really become fairly useless after that initial rush period since axemen are about the same strength and far less vulnerable. And they don't particularly shine as auxiliaries either, in the way that Impis and Gallic Warriors do.
It's particularly bad because the Sacrificial Altar is fantastic, and imo a far more worthy item to base early development around. By the time you've beelined CoL, you want the extra punch that swordsmen provide for taking cities, and it would be great to be whipping them out en masse everywhere to overwhelm the entire continent with your endless Aztec hordes. Except the Jag doesn't give you that punch, so it hinders the hell out of you and you end up whipping mostly just massed axes and racing for construction.
For an Aggressive leader to lose one of his mainline melee units to gain an auxiliary of dubious use, right at his point of dominance, is really unfortunate in my mind. The cheaper cost is negligible, but it's just enough to be an annoying hindrance to easily whipping away 2 population at a time.
I've used a modded Monty with just normal swordsmen instead, and he was devastatingly powerful.
It's a real shame, because otherwise Monty is a fantastic leader, and the jag is undoubtedly just the damn coolest looking unit in the game.