OK, ok, I'm at my breaking point, throwing in the towel and reverting to my plan for booting from an MBR SSD.
I cannot spend anymore time trying to get BIOS booting of Windows 7 on a GPT drive working. I really wanted to get this done, to implement the Rubic's Cube solution as it were, but as Wonko pointed out to me I can achieve all but 1 of my desired goals so why bother with GPT on a small SSD? That one goal was to rid my system of all MBR partitioned drives. That appeals to me and it would be nice, but not necessary. I have reached my threshold of effort to get this done. Good luck to those of you who continue to try. I will be keeping my eye on this thread, for sure.
I thought with all the reports of "success" I read in this thread (and some on sevenforums) it wouldn't be so difficult, but my conclusion is just the opposite. This topic has been around quite a long time now, so if all these efforts have led to even 1 solid, acceptable, repeatable solution why has nobody summarized the process into a list of steps to follow?
Wonko commented to me that I was trying to mix too much together, yet his approach to booting Windows on a GPT HDD requires much deeper technical prowess than my use of existing elements in a typical manor (i.e. grub2, memdisk, vhd virtual drives), and is also far more complex than Sacha Weaver's.
Had it not been for the lack of the "raw" memdisk parameter which cdob pointed out to me I would have gotten to the Windows setup screens with relative ease (Weaver documented the process quite well), succeeding in grub2-->memdisk-->bootmgr.vhd( bootmgr/BCD )-->setup.exe on a GPT drive. I thought I had it made in the shade when I saw the familiar "Starting Windows" fireflies, but noooooooooooooooo!!! Windows was not happy with that boot sequence and refused to complete the setup process. The impression I got from Weaver was his approach was a final solution. It wasn't that much different than milindsmart's, yet I didn't see others claiming they were able to repeat his success. Was it a one off? Did he leave off another crucial step? Perhaps he too assumed complete success when he saw the fireflies and was embarrassed to post a clarification. He was far more comprehensive in describing what he did than many other posts in this thread, but can it be repeated? I have my doubts. I know I wasn't able to with the steps he provided, but I did get close!
Is that why this thread is titled "Hacking bootmgr..." rather than "What it takes to boot Windows from BIOS on GPT without UEFI" ? How could I have missed that? Perhaps b/c only a small minority of posts in this thread actually deal with "hacking bootmgr" and instead deal with alternate boot methods to reach bootmgr (transcending real to protected mode), of which I myself can claim success, using Sascha Weaver's approach. But so what? Once bootmgr runs and launches the setup for the install.wim deployed by imagex, it fails in a bright ball of flames and results in a useless, incomplete installation.
It's really easy to get lost in this discussion, but my conclusion is that no summary or tutorial exists yet b/c the process is still elusive. Does it require hacking bootmgr (i.e. disassembly, hex editors, patching or reverse engineering etc) to be able to boot a fully functional non-UEFI Windows 7 with a legacy BIOS resident on a GPT disk, or, is it a matter of tricking the bootmgr with some script, registry change or unattend.xml to satisfy it's overly restrictive conditions that prohibit setup to complete and lead to a functional system (or allow a previously installed and functional installation to run properly) when it's %SYSROOT% is on a GPT drive?
I will admit my lack of recent professional experience when it comes to Windows IT, I'm near retirement age. I may be drawing a wrong conclusion, and someone with detailed understanding of sysprep and enterprise deployment will look at this and point out a simple solution to the incomplete installation, and if so great, but I can't wait around for that. I've spent too much time chasing this tiger as it is.
It will be interesting to see what comes.
Thanks for all your efforts!