I'm not a pro, but I do have a 921 and here's a few things you may want to know :
The remote that ships with the 921 sends ONLY RF commands to control the unit ( it will send IR to control other brand components such as TV's, VCR's etc. though, go figure why they did that ). So if you need to directly "teach" any IR commands to the RTI, you'll need to buy another Dish remote on Ebay such as the 522 (TV1) remote, they're cheap . The receiver is rumored to soon have the ability to teach all IR commands directly from the receiver to a universal remote, but whether that will happen is unsure given Dish's past broken promises .
Also, all Dish remotes and receivers can be set to 15 different unique addresses so that they don't interfere with each other in a multi-receiver installation . So if you download IR codes, you need to know what address it is and set the receiver to that address . They originally didn't ship with descretes, but I think they have them now .
Lastly, the 921 is scheduled to have a software update in the next week or so to fix some of the problems they've had, mainly to do with OTA recording . Here's a great site to learn more :
[Link: dbstalk.com]