I am curious why you say this about the keys. Do the gemstone keys work differently under the cover? I certainly agree that used MX850s carry risk. Many sold on Ebay are essentially worn out.

I gather the Xantech IR system is a remote repeater. It should work fine. Also, do you have access to the Editor Program that you will need?

I am a retired salesman who learned to do basic programming. I love the MX850/800 and still use it after all these years. It is so easy to find the buttons in the dark, it feels right in the hand for me. As we record rather than channel surf I use the previous channel button for the skip task.

I also use Eneloop rechargable batteries so battery life is not an issue. I always have a backup set ready to go.