RS2e arrived today from fellow forum member with about 100 hours on it already. Duel with the GH2 will start in earnest tomorrow. Very close in sound from just an hour or so comparing with music I know best. More later ...
OK, so I've had a couple of evenings with these two. For testing, I am using the stock L pads on both headphones. Normally, I use the large G pad along with some plastic spacers I made from, of all things, Barbasol shaving cream tops with black gaffer tape on them!
For some context, I listen to rock (classic, prog & pop), some metal (Dream Theater, Tool, some Opeth), jazz (classic, fusion, bebop, contemporary), acoustic / folk, electronica / EDM, and a little bit of classical and country for good measure. Very guitar-centric for the most part, which is completely why years ago I tossed my Senn 280's in favor of Grado SR80e, which then led to the inevitable Grado ladder climb. Unless I win a lottery, one of these 2 will be my TOTL headphone (with only a couple of other semi-tossers at home).
Here is what I am hearing when I compare these two. With the RS2e, I understand the Grado "Reference" series name. These are very precise phones, with a very clear instrument placement and imaging. This is especially noticeable with jazz or acoustic or simple rock with only a few instruments in play -- nothing is ambiguous or hazy about each individual instrument. Even on busier rock or jazz large-ensemble settings, like Radiohead "The National Anthem" from Kid A, multiple instruments remain clearly defined and don't smash each other out. On some especially loud stuff (DT, Tool, etc), a good test for headphones is this: do heavy, fast kick drums drown out or over-power a vocal or keyboard solo? Sure, the production / engineering of the music and the quality of your sound files can help / hurt this, but a good headphone can present a delicate vocal or cymbal ride on top of a pounding kick drum or bass guitar line, and both remain "in their own lane" so to speak. I really hear this with the RS2e.
The GH2e (cocobolo wood), by contrast, comes from the "Heritage" Series, which I think of as more experimental and one-off designs, whether is it cup material, cup size and shape, driver size, etc. With the GH2 the instrument placement is hair fuzzier, and the over-all sound is a bit more atmospheric, wider sounding. To my brain, it's like the GH2 has the "surround sound" setting set at 1 or 2, whereas with the RS2e it is off, so to speak. You have to listen to the GH2 with a bit more attention to hear the same detail level as the RS2e. To be clear, I hear the same level of detail in both phones, but with the RS2e the details are more obvious. I think most people describe this at more transparent.
So, for me, the GH2 lends itself to slightly more atmospheric music, OR times when I want to be more immersed in the overall music rather than the details of it. However, my brain is very analytical and to me the RS2e just "makes sense" a bit more with its more exact imaging and instrument placement.
Other people on this forum have done great jobs at dissecting the bass, mids and trebles of these two phone. To my ear, they are extremely close, which makes me think that they are both likely using the exact same driver, but differ slightly in sound do to whatever tuning Grado does to achieve whatever target sound they want and the differences the wood housing contributes. Both have great, clean bass response and depth, but not quite the extension down into the sub-bass region of 40-60K you'll find on a closed phone. Both have the Grado very-present midrange that make nearly all vocals shine and really standout, although the RS2e is a tiny bit more mid-centric, which is consistent with mahogany wood vs cocobolo -- the GH2 is slightly more V or U shaped. And both have very smooth trebles all the way up past the sound of a gentle stroke of a wire brush on a cymbal. The RS2e does have a bit more of the Grado 2+K up-tick and on some songs at higher volume exhibits a bit of the hated Grado "shouty" sound.
All in all the differences between these 2 phones are very small and both are exceptionally fine sounding headphones that are well-worth their price. It make take me a week or more to decide, but it is very possible that a very nice GH2 may soon be seen on the For Sale forum!