The level 19 ability is the strongest one they have!
I'm not convinced. That's a really tough ability to judge, and honestly there's not a lot of abilities that stand out to me as ZOMG AWESOMENESS that also happen to be Ex. (unless you're counting Spells, but I'm going to assume you're not counting Spells because that's just silly, and Factotum would be a T0 class if that actually worked)
I love the assumption that you become a TO class if you have the powers of a Sorcerer. It's accurate I suppose.
But ignore the spells thing, Fighter Bonus Feats are a single Ex ability. Congrats, for one fight a day you just gained every class feature the Fighter has (I recommend getting all the archery feats, you can do quite a lot that way and it's worth having a solid bow anyway. But since you pick which feats you want when you activate the ability, you can chose according to the monster you're fighting). Warblade or Swordsage maneuvers are another fun one. Flurry's not bad either, depending on your setup. And nothing stops you from activating multiple at once (other than your number of inspiration points). You could just decide the BBEG needs to go down NOW and take all three of those things at once, then charge him with Spirited Charge, Shock Trooper, full Flurry, and the Pouncing Charge maneuver. Why not? Sure, it's a Nova tactic, but it darn well works.
JaronK