I do universal imaging with Windows 7. However, I moved to creating the base image in VMware, but when I did use physical hardware, I would normally create my base on the lowest supported model and move up.
I would check out the sysprep logs and see if there is anything in the logs that is telling you why the machine is not booting further than a certain section in sysprep, it could be as simple as having something wrong in your sysprep unattend.xml.
Your sysprep logs are here:
Generalize - %WINDIR%\System32\Sysprep\Panther
Specialize - %WINDIR%\Panther
Setup actions - %WINDIR%\Panther\Unattendgc
once it errors, and hits a reboot cycle, go into WinPE and browse to those directors and open up the logs with notepad. Should give you some good info and maybe we can pinpoint what is happening.