Disk Utility errors trying to Partition

The problem appears to lie with Sierra's version of Disk Utility. It's buggy as ****, so beware. I managed to recover using an older version of Disk Utility from a network install service, but when I retried Sierra's Disk Utility did the same thing: It hangs while "Resizing Core Storage Physical Volume structures." And if you force-quit it, it may or may not leave your hard drive in a corrupt state with regard to partition sizes. That state took all day to recover from, painfully.

Almost as bad, if you try to create two 32GB partitions for a total of three, you can easily end up playing whac-a-mole because of the way partition sizes are determined relative to your main drive. In other words, if you create a 64GB partition for El Capitan and then try to split that one for Yosemite, you can never resize either of them predictably. You have to split the main Fusion Drive each time to avoid this SNAFU. That means you have to wait forever for your main partition to resize itself, but at least you'll avoid the whac-a-mole problem.

I have yet to see Sierra's Disk Utility complete a partitioning job without hanging with the spinning rainbow cursor of death, so this app should not be shipping with Sierra GM.