I didn't really pay attention to the file cards, but Zombie-Vipers are obviously more than just standard shamblers.
Compound Z appears to more like the T-Virus in Resident Evil, as it affords some serious mutation (the tendril arms). There's also the "control helmets" and canisters included with the Zombie-Viper.
I think Compound Z might not be the reanimation agent itself, but a mutagen that makes zombies more useful.
I'll consent that standard "walking dead/OTD" style zombies are useful only as a terror weapon, but I'm thinking Compound Z affords some benefits to the Zombie-Vipers normal walkers don't have. Be it speed or just enough more intelligence to make them controllable than a walking plague, it definitely gives them SOME advantage.
I can absolutely see BATs being used to clean up areas where Zee-Vees were deployed. If they make too much of a mess, infest too much of the target population, just use the BATs to clean them out. The Zee-Vee's won't care about BATs any more than they would about a vending machine, even if they are armed.
But think like COBRA guys, not how to use BATs against Zombie-Vipers... but how to use them together.
One BAT vs. one Zombie-Viper, of course the BAT is going to win. But BATs have to be a serious investment, and even if they can be repaired or self-repair, they can't self replicate. I do think both should be considered weapons and not troops. They're tools, and each has a specific use they would excel at.
I know some people are sick of the zombie trend, but common... it was the robot trend of the 80's that gave us BATs. They're both born of ridiculous sci-fi tropes, the fun is trying to figure out how things like that might actually work!
