RD-M6000 GS vs. SGS
 

The GS version is on the left and the SGS is on the right. The GS is rated for a 42t cog & 41 links with a double front, and and the SGS is rated for a 36t & 43 links with a triple front.

http://productinfo.shimano.com/image...k_S1_draft.png http://productinfo.shimano.com/image...k_S1_draft.png

I thought this was interesting because it looks like the front knuckle is different to clear the larger cog, and the cage is almost the same length. This is pretty much the opposite of the traditional situation! I wonder if the clutch is different or only its housing. The cages look very similar but are not the same. The M7000 units are the same way and many of the parts are interchangeable from 6000 to 7000. The rear knuckle is also a different shape - look how the cable stop is carried higher on the GS.

the tech docs are up- it appears that the GS version uses an offset pivot, while the SGS doesn't. unless you're going 3x, i would always choose the GS version, it will follow the cassette much more closely without as much b screw necessary

I haven't found them for sale yet but I'm watching.

what you can't find this anywhere? i can find this on my country (Indonesia) quite often :/

M615 yes, M6000 not yet