I am an optimist. I'm a fairly competitive player (at least I was in Mk 1, and I'm just getting back into the swing of things now), but I never write off units entirely. Still, as we all know, some units are just a little bit less competitive than others. Some casters make you sigh, some warbeasts and warjacks don't often see the light of day. Rather than ask PP to simply "fix" the model, we should look to the future. After all, PP isn't going to errata all of their books and send out new cards until Mk III, years from now. However, we are getting a new Warmachine book next year and a new Hordes book at some point in the future (one assumes). So rather than look at what needs to be changed on existing models, think about what could be added to them in later books-- UAs, solos, warcasters, anything-- to help fix what's broken.
I'll give an example of what I mean. I like Praetorian Karax, but I know that compared to Swordsmen, they're just not all there. What about a UA-- Praetorian Karax Officer and Standard Bearer-- with Tactics: Brutal (or Powerful) Charge, Granted: Combined Arms, and the minifeat Defensive Formation like the IFP UA? Karax are slower than Praets and having to Shieldwall slows them down further. They have a greater threat range on the charge, however, due to Reach, and Combined Arms would help fix some of their accuracy problems when doing two-man CMAs. A unit with Reach, CMA and Ranked Attacks would fulfill a role sort of halfway between Swordsmen and Cataphracts, hitting hard on the charge and soaking up damage admirably.
Don't just think in terms of UAs. Zerkova would love to have a decent target for some of her spells. Think of how great the Castigator would be with a 'jack marshal that could Drive it to use a *action after charging! Sky's the limit!