Alright, so my green dampers came in and I auditioned them pretty briefly against the browns.
Green / 1500 ohm:
Thumping bass but with relatively little sacrifice of soundstage. These are heavier and less crystalline than the browns, but nowhere near as muddy as the reds start to get. Not bad, but the greens really pull back from that mid-forward Shure sound and crank up the bass. Fun, but way too colored for my stock setup (if you need more bass, maybe try EQ?). The highs are still there, but they're taking a distinctly backseat to the bass and you need to strain a bit too much to hear the details. An acceptable setup, but not for me.
For my personal rig, the browns stay. That said, I would consider the greens an option for someone who really wants to punch their low end through the roof without losing the rest of the music. Green seems like the floor of a usable hi-fi setup, any higher resistance you are going to really start missing out.
A reminder of what we're talking about regarding tone shaping, refer to Rinchoi's sweet charts here: http://4.bp.blogspot.com/-TWX_XiD-gRM/UYaCcpX0TeI/AAAAAAAAGAU/Y7Irw52aWYM/s1600/damp.jpg
I'll edit my original post to include the green reviews as well.
Looking forward to listening notes from the rest of the modders cropping up here!
Lastly, while I'll be holding onto the whites, grays, and browns for future messing around that does leave me with a bazzilion orange dampers and a few reds, yellows, and greens I'm not going to keep.
To share and share alike, I propose the folllowing:
I will mail all my extra dampers to the first person in the USA to PM me (sorry non-'Mericans, I'm lazy with postage). No charge, but I'd suggest that individual offer the same to others in turn, paying forward any unused dampers. So, any Americans want an envelope full of bassy dampers?