In this day and age I would rather a program like MBam to be over zealous than risk encrypting an entire drive with ransomware. Once you have verified that the file in question is "virgin" and not infected just add it to your white list.
Ok, I admit I am an "completionist" and working on the MAME collection first. Given that, what size drive would you think I need to house all the ROMS, and CHD files just for the MAME side of things? I can easily see this is going to spiral out of control and trying to just allocate some space on my NAS dedicated to just this project...