Got my R-09HR today :) Nice little recorder. It definitely feels more robust than the R-09. I'll take pictures some other day comparing it to the R-09, unless someone else wants to before I get around to it.
I did a couple quick tests, one being an ADC test (will post the link here when the files are done uploading). While I don't know how to measure unity gain, I did a quick test on the gain structure. I recorded a sine wave from my iMac > recorder line-in. At the particular output level of my iMac, we get the following:
R-09 (level, peak) (reference standard at supposed unity gain level 8):
8, -24.2dB
13, -19.6 (default input gain)
R-09HR (level, peak) (default is 40):
40, -21.5dB
39, -22
38, -22.5
37, -23
36, -23.5
35, -24
34, -24.5
33, -25
I did not run further down or up to see if this "half dB per gain click" continues to hold true. According to this, levels 35 or 34 would best approximate the R-09 level 8. For my ADC test, I chose level 35.