virtualbox.org

I'm looking for a nice way to batch move a VM from one machine to another where the VM uses an iSCSI target (this means no export/import).
VBoxManage showvminfo --machinereadable <name> sounds promising, but I can't find any form of createvm which uses the "machine readable" form as its input. Wouldn't it be an obvious and easy addition for createvm to be able to input the machine readable form output by showvminfo?

What about simply removing the VM from one side and adding it to the other, since I guess both hosts can access the iSCSI disk?

I don't completely understand your response. What is "simply removing the VM from one side and adding it to the other"? Doesn't that mean I have to create a roughly identical VM on the new host (and at least shutting it down on the old one)? That would seem to be done with VBoxManage createvm and modify commands, but wouldn't it make more sense for there to exist a form of the VBoxManage command that would take the machine readable output of showvminfo as its input? That just seems logical to me.

Your VM folder already contains the VM definition file, with all the infos, and the disks for the data. So by default in 4.x, your VM is contained in a single folder that you can transport easily.
In Virtualbox, you have a "Add VM" function (called registervm in vboxmanage and "Add..." in the GUI) to import this definition file and have that VM appear on the other host.

Be sure that when you do that, you also un-register that VM on the original host (unregister in vboxmanage, Delete | Do not delete files in the GUI) or you may run into permissions issues.