I asked about using the units separately, such as letting a friend use one of the units. Here is most of the response from Kevin
Initially, the plan with the Z2-4 was to have a Master/Slave config where all connected units would be controlled through a single interface, and a 240V power supply in the head unit would distribute power to the other units.
Someone realized from a manufacturing standpoint, it's much simpler to build, manage, and track one type of machine (technically two considering international 220/240V models) rather than two types (again, technically three), and only moderately more expensive to have an interface on all units rather than just the controller/head/master/whatever you want to call it.
There's also the issue of someone having a 110V Z1 that may need to be upgraded to a 240V later if someone wants to expand their system.
So, as it stands currently, all domestic Zs are technically a 110V, but in the case of Z2-4s, a 240V power supply is being split to multiple 110Vs as most standard 110V circuits won't be able to handle the draw of more than one machine.
Each unit can be controlled individually, and will have its own WiFi or Ethernet connection to the AP, however one of the planned firmware updates will allow a batch to be started on one unit, and have it so that the recipe program pops up on other units so that the user has to navigate a ton less to start a session if the same recipe is being run across multiple units.
In regards to loaning it to a friend, it will be able to operate individually as a Z1, however, because it is associated to your account, they would need to be given your account credentials in order to interface with the machine, so I'd make sure that it's someone you trust