This post is not about downgrading from lollipop to kit kat in general. It is SPECIFICALLY about and it is ONLY about downgrading the BOOTLOADER (motoboot.img) and the PARTITION TABLE (gpt.bin). The system (system.img) and kernel/ramdisk (boot.img) are NOT the subject of this thread. If you don't understand the difference b/t the bootloader, partition table, system and kernel/ramdisk, then please refrain from posting on this thread and simply read until you understand the difference.
Please do not comment if you do not even know the version of the bootloader you are running b/c you have nothing substantive to contribute then. If you know the version of the bootloader you are running now and know what it was before you upgraded and after you downgraded, great, please let us all know your experience. But if you don't, AGAIN, you have nothing of value to contribute to this thread.
The Moto X 2014 is not a Nexus device - you CANNOT safely downgrade your bootloader (motoboot.img) or partition table (gpt.bin). You risk bricking if you do, especially if you downgrade the bootloader!!!
You need to understand what you are flashing. If you don't understand what you are flashing, read and ask questions before you flash until you do understand what you are flashing. You also need to know what version of the bootloader you currently have before you flash.
Also, you should not attempt to have a bootloader-partition table mismatch in terms of versions. Both your bootloader and your partition table should be the same version - i.e., if your bootloader is the 5.0 bootloader, your partition table should be the 5.0 partition table.
Edited - it looks like mfastboto and maybe even regular fastboot have checks in them to prevent a bootloader or partition table downgrade. However, the OTA updater scripts may or may not have sufficient checks in them to prevent bricking if you have previously upgraded then downgraded the system/kernel/radios and then attempted to take an OTA. For instance, people have reported bricking after flashing to 5.1 then downgrading system/kernel/radios to 4.4.4 then taking the 5.0 OTA = brick.