LOL, I have been on a goofy journey the last 24 hours. Win7 UEFI is very common, but if you try and allocate some space to do a win10 install on, the setup system seems to purposefully break the current bootloader and installs a new bootloader that Win7 UEFI is for some reason incompatible with. WHAT?! I mean, you can just intercept bootloader by hammering the key on your keyboard during boot and selecting the win7 drive/partition...but why is it like this? I've gone through a couple different methods of installing a dual boot win10 on an existing win7 and it straight up fights you all the way.
Win10 was an alright experience, but I'm very happy with Win7 and don't want to have to go through with this boot process every time I boot my comp.
The design of the system is to make it difficult to install win10 alongside win7, although you are encouraged to test it out, without realizing it will break the bootloader and leaving most people without many options. So you can 'upgrade' and essentially lose win7, or you can 'test' win10, and regardless of the 'default' win10 install, or your efforts to make a custom GPT formatted layout on additional attempts, it will break the bootloader...apparently with a specific intention to do so and leave one booting immediately into win10 or a broken reference to your win7 boot in the bootloader.
Like, pretty much the only option is to physically disconnect your win7 drive and all storage drives, plug in a blank drive for a win10 install, install win10, power down computer, plug everything back in and use the disk boot priority of your bios to boot the system you want. Ridiculous. This is what I used to have to do when testing random linux images due to conflicting grub/syslinux vers etc. I mean, it's not even like that anymore in the linux environment and MS has an entirely controlled system. How can you even argue that they didn't design it this way?!
Your either going to test it out and like, or discover that returning to your previous setup is either impossible for the user or extremely difficult for the mildly tech savvy...and even then it's super time consuming.
Edited by czerro - 7/4/16 at 12:12am