The R50 and R40 were discontinued several years ago. Some years back I replaced my MX-500 with an R40 and it was probably the best learning remote i've ever had, but it has the dreaded OLED screen and it went dim within a few years. I bought another one and that went dim too. The earlier models also had a firmware issue and commands would disappear (but fixed the later version). I loved the ergonomics and button layout. It uses the same housing as the MX-780.
I also briefly had an R50 and it's fairly decent, but i replaced that with the current model MX-450 which is the Pro version, and it is better built (i like it much better). There are a few functional differences, but they both have an LCD screen so they don't grow dim over time.
My wife loves her MX-500 and has rejected all attempts to switch her over to the MX-450 in her den.
Randy URC MX-890, MX-780, MX-450, R40, MX-500, Sony XBR-55X900E, Panny TC-P55ST60, Tivo Roamio Pro & Premiere, TWC Arris DVR, Onkyo 333 AVR, Panasonic Blu-Ray . . . .