The plastic quality on the KO Binaltechs is slightly weaker, if not about as good as, the real thing. They even include die-cast in the vehicle shell pieces! Construction quality and tolerances, however are kind of poor. Both of the KO Binaltechs I have, Dead End and Silverstreak, aren't able to store their weapons away as the engine like they're supposed to.
In short, if you're okay with owning a KO, and have no plans to display them in robot mode, they're a decent substitute for the real thing. But I would rather get an Alternator of the same character where possible. Less worry about scratching the paint on the metal parts.