I use firmware made by a Russian user (should be links to it in the R10 thread). Much faster UI and improved sound.
Most songs sound better to my ears but the Groove does have a bit more low end than the R10.
Also tried the Groove on my Chromebook and it works. So it seems to be plug-and play with everything except Windows (for which you'll need to jump on 1 leg to get the drivers).
With my Note 3, there is some static (popping) when playing music through the Groove. The Groove doesn't get quite as hot when connected to the Note 3 vs. a computer so I'm betting it's a bit starved for power but it works. Static happens in UAPP and Pandora. No static in VLC when playing movies though but, strangely, static returns when playing music using VLC.