thanks edmund, very helpful.... i used the mx-500 back in 2004 or so, for about 5 years, and then moved on to newer and more "modern" remotes... but none of the newer remotes ever really did it for me, for many reasons, so i decided to return to the mx-500... since mine was long gone i went to ebay, and was surprised to find many different models, for a song compared to what i paid for the mx-500 back in the day, so i picked up an mx-500 (absolutely mint), an mx-600, an mx-700 and an aeros mx-850....

played around with all of them but settled on the mx-500, again, really like the black, but recently noticed that the 850 offers rf, and now that i've looked at all of them closely, it looks like the 600 and 700 are rf capable too...

but after a bit of reading i think i may have misunderstood the rf functionality, it appears that the rf is used with the base unit, which then converts signals to i, as opposed to being able to program rf remote controls into the mx, do i have that right?