I just hooked up my HD-XR yesterday, and am thrilled with it. Only one issue...perhaps.
Though I have all the qualifications for 5.1 audio per the FAQ (high-end multi-channel Marantz receiver, HDMI 1.3a hookup, super-fast cable connection, 4-stars on everything, 5.1 Audio selected in the setup, etc.), none of the Netflix HD selections I've watched, so far, provide anything but stereo.
I know not all the material is 5.1, but you'd think at least one of the 6 HD shows & movies I've viewed would have it -- especially when they're HiDef. My cable programs unfailingly read out 5.1/Dolby Surround when it's present int he programming -- but so far not on my Roku. Not even Pandora, but probably because it's lossy stereo only.
Otherwise, it's an awesome gizmo