What are the pros and cons when comparing the two, 6V 1/8" shaft vs 12V 1/4"shaft feeder motors beyond the obvious of throw radius distance, durability and feeder sound for the animals to hear? Any cons like excessive corn consumption on throws, etc.? Currently have 6V, considering changing out to 12V especially in light of expanding size of feeder pens. What Say the THF?

I have 2 6v feeders at one stand and 2 12v feeders at another. The 12v do throw corn farther, but the cages almost just drop the corn under the feeders.. Other than that, they work the same. Batteries last about the same, many years. I have solar panels on all of them and cages around them for the coons. You can control the throw rate by feed seconds and gap from funnel to spin plate.
But, if I had to replace any, I would go with the 12v with good timers.

12v motors are fully sealed so they are much more dependable.......and throw the corn much further if you don’t use out of date technology like coon cages.....

More speed and torque from 12v as opposed to 6V, greater Ah in 12V batteries.... why not go 12V?

You don't necessarily have to go with 12v. A motor's ability to do work is based on alot more than simple voltage. It's RPM and HP ratings tell the tale. A 1/4hp motor does the same amount of work whether it's designed on 6v or 12v, just the amperage rating changes with the voltage (Ohm's Law). You can get 6 volt motors with the same RPM and HP rating as the commonly available 12v feeder motors. They aren't as common, but they can be found. If you go 6v, just parallel another battery with it for additional AH capacity and you are just as well off as with a typical 12v system.