But all your systems are already licensed. You are not building systems to sell so you can't use an OEM image. (Basically a system builder like Dell or Joe's computer shop can create OEM images to deploy to the systems they sell.
The Volume License is only a licensing loophole to allow you to create your own images. The installs will activate using the OEM Win10 Pro key that's already part of each machine. Now i know normally you can just contact microsoft and have them up the MAK activations, so is this the same now with Windows 10? One follow up, so if i buy one of these volume licensings the MAK usually comes with 50 activation.