I have both. the d50 is by far the better sounding and better built unit. Advantages would be rotary gain and headphone knobs, quieter preamp,
optical in and out, better metering and a powerful headphone amp. Disadvantages would be larger size and 4 AA batteries instead of 2.
The d50 has position adjustable cardioid mics whereas the r-09hr has omni mics. As to which mics sound better, that would probably vary
according to application. I would buy the d50 without hesitation.