Can I flash an unlocked G900T bootloader on a G900A?

I have a G900A and a G900T (short story: couldn't live any longer with the locked bootloader on G900A so I bought a G900T to use on AT&T). It's possible to flash a custom recovery/ROM onto the G900A, but it seems that the bootloader will recognize things as not being signed on boot and will not allow booting.

However, if I were to flash the G900T's bootloader onto the G900A, I could potentially bypass this restriction. Since it's basically the same hardware, it should theoretically work. Not wanting a hard brick, is my logic correct? What facility examines if the bootloader is signed? Will it allow me to flash an unsigned bootloader in Odin? Is the bootloader truly the source of the locked problem?