The only "added feature" is the RF extension capability, otherwise it's identical to the MX-700 behavior. In addition to IR (infrared, line of sight), the MX-800 can emit RF (radio frequency, aiming not required) to the RF base station, which received the signal and converts it to IR. So, you can use the MX-800 in your bedroom, and the signal can go to your den (where the MRF-200 RF base station is) and control your satellite receiver.
We've found that many customers are using the remote to leave their equipment (TiVo's, satellite receivers / cable boxes, DVD players) in one location, and be able to control it from across the house. It's terrific for X-10 as well: Put the IR543 with the MRF-200 and control the lights from anywhere in the home.
I hope that helps, obviously there are myriad applications and uses, but other than the RF capability, the MX-700 and MX-800 are the same remote (with a different color!)
As to your specific question of "Is it worth it?", I would have to answer with an unequivocal "YES!". For the small entrance fee ($500 vs. $350), the RF capability AND the included MRF-200 base station is a great addition, without requiring the use of a seperate RF transmitter (as it's built right into the MX-800).
David
www.BlueDo.com
