slanted & enchanted wrote: i figure it'll be better than trying to transfer half carbonated beer between cornies. that sounds like a foam nightmare.
No, it's quite easy.
Fill a clean keg with sanitizer and push all the sanitizer out with CO2. Leave this empty, sanitized keg with 10psi (or whatever your full keg has).
Arrange your kegs with the full one on a table or something and the empty one on the floor. Connect one jumper between the beer posts and another between the gas posts. A Tee in the gas jumper is nice in case you need to boost things along near the end. The whole arrangement looks like this:
A very short vent on the lower keg will start the beer flowing. Then it will gently siphon itself from the upper keg to the lower keg with no foaming at all because the beer never feels a pressure drop.