Hi Joe,
Can you send me the SR number to myusername@vmware.com ? Your use case is interesting, i.e. reverting to an OS with an older driver. I agree that the current behavior (that the guest driver is choosing the supported capability) and possible corner cases should be documented better. You can override (without having to remove the the other option) via: vmxnet3.disableLargeBAR
Cheers,
Valentin