That's the point! I don't need to replace anything any more. I just take my remote controls with all their buttons and just attach them to a simple piece of plastic that will keep them together for ever. I never loose them, I don't have to program anything, and best of all I don't have to spend 3*115=$345 to gain the same functionality as you did with your mx-500s. Plus it is still pretty easy to loose your mx-500s. Check out the comparison:

[Link: store.yahoo.com]