1) I use the MRF-250 because all my equipment is hidden behind closed doors. Even if my equipment were exposed, I would still use it so that I can be anywhere in the house and control all my lights with the MX-900.
2) I do not believe the IR543 sends out IR. It's called the "IR"543 because it converts IR signals from universal remotes to X-10 commands. Think of it as a IR version of a RR501. The IR543 receives X-10 commands via IR instead of RF, and and then sends them through your electrical the same way the RR501 does.
Hope this helped.
"People are very open-minded about new things -- as long as they're exactly like the old ones" Kettering
