So, I bought this adaptor to backup my NES saves and it worked surprisingly well! Only complaints I would have is the adaptor is not as easy to use as the other built-in options. From what I can tell there is no auto-detection for NES carts. You have to go to the NES cartridge forum and find the setting for the specific game you want to backup BEFORE hitting anything on the S.T.H builder. After punching in all the correct cart information it works great, but you have to be very specific beforehand. I put some labels on the back of my carts after backing up just for future use. Also the file structure doesn't remember the name of your NES game with this method so I'd advise doing your backup and then plugging it into your PC to change the names of the newly created files before you move on.
Also, it is pretty thin and flimsy feeling so to make it sturdier you can saw an unused SNES cart down and put this board into the empty shell. It is designed to drop in perfectly and even matches the keying so you can't insert it backwards. After about an hour of sanding, applying some hot glue and cleaning up my custom Cart it looked like this. Even added the Ukraine sticker to complete the look i wanted. It's much sturdier now and looks great. Hopefully this gives the next buyer some good ideas for their own build.
Thank you again SaveTheHero! You are preserving my whole collection and a history of my childhood game saves going back over thirty years.