EDIT:
I learned how to program the MX5000 for network IP Control.
Using that instead of RF makes it WAY faster.

Menu up/down and volume up/down are just as fast as the OEM remote now!
Night and day difference.

IP control is not as complete a solution as IR though.
Just FYI to anyone reading this. Some buttons are not available that you see in IR. Not sure if you can "learn" an IP Control button?

If you want to learn basic IP Control programming, then @BizarroTerl has a nice walkthrough here that got me going:
[Link: remotecentral.com]