A couple of points here.
-I thought the point of distinguishing between Warlord and General was that the higher point characters purchased later would able to be General, but wouldn't have those slick warlord upgrades. Seemed like a good way to balance it. Warlord was sort of a lesser commander that, at some point, goes to the king to become a part of a larger army.
-I want to run my Miser, but your warlord xp tables will be incredibly broken with the Miser. Especially that Unbreakable rule, as dying to CR is his kryptonite - with unbreakable, he'll become something you can't kill without an overly focused approach.
-A Miser properly outfitted for a 4500pt list is about 1000pts. By having a reoccurring warlord bought within 600pts, you prevent from fielding the Miser until the character allowance is Warlord + 1000pts, which should mean that I can't field it until my opponents can cope with it.
-In case the 1000pt price tag makes you nervous, Miser is really offensively weak, so much to the effect that he's not really fielded in tournament lists. He's like a really big punching bag. Should be fun for casual play, though I'm told the common tactic against is to just ignore him because, again, he's really offensively weak.