ok so not surprisingly, there is a a lot of wrong, old, or straight up misleading information out there over what very programs can do and how. With DiskGenius FREE edition, yes, you can clone a drive and have it be bootable. Their own guides were wrong. Don't use Disk Clone, use System Migration instead. System does not just mean OS, it means OS, files, installed programs, everything. After you create this 2nd disk, restart, I allowed to complete the cycle and come all the way to windows, then I shut down. As others have said about the old adage, when in doubt about seeing boot priority, take out the drive. I removed it, kept in the new one, did nothing new with bios, and it booted windows fine under the default of CMS/legacy. Installed apps (Halo Infinite) also work.
Next is converting to gpt.
When I use DiskGenius to convert to gpt, it says I need a few dozen open sectors on the head and tail of each partition. It's easy enough to do this with the program, then convert to gpt. But upon doing so, it says the OS will become unstable. Big bold red letters. I do it anyways, reboot, and once i get past bios I get 'insert bootable media error'. Go through the cms/uefi, cms/legacy, cms disabled dance, still not bootable. Only recourse is to plug in the old drive, re-system migrate, reboot, unplug old drive, and now back to where I am now.
Is gpt really worth it? Ive heard it both ways, the gpt helps with boot times and it does nothing at all. I'm only using one partition, and this pc is just for gaming/office work. Will gpt help with game load times?