The new quad core Atom CPUs are great for 1:1 devices, long battery life, support everything and not too expensive, problem is imaging them. The issue with MDT imaging is that they are detected correctly as 64 bit architecture and so copy 64 bit EFI. This should work fine but most of the vendors have crippled the EFI implementations to only support 32 bit EFI. Some tablets support PXE with a USB NIC like the Acer Aspire Switch 10, others like the ASUS T100 don't. Either way if you are trying to use MDT it will happily fill them with un-bootable EFI code.

Turns out that the detection algorythm used by MDT is largely WMI and as such, you can just tweak it to look for the offending processor type and switch to 32 bit instead. After a good hour in the company of notepad I found this:

On line 515 of ZTIGather.wsf

replace all of case 9 with this

' Compensate for bad EFI on atom units. WMI ProcessorId BFEBFBFF00030678
			Case 9
				If objInstance.Caption = "x64 Family 6 Model 55 Stepping 8" then
					sCapableArchitecture = "X86"
					bSupportsX86 = true
					bSupportsX64 = false
				Else
					sCapableArchitecture = "AMD64 X64 X86"
					bSupportsX86 = true
					bSupportsX64 = true
				End If

In our implementation this seems to have worked nicely, hopefully it saves someone else some frustration.