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Which 2x9, the granny and middle, or middle and big rings?

Road derailleurs generally can't get out to the 48-50mm chainline that MTB cranks use.

And you're not going to be able to get road cranks to work as you still need clearance between the inside of the crankarms and the lower suspension linkage. The 147-150mm Q factor road cranks won't fit around the lower linkage. Most current external BB MTB cranks have a 170mm Q factor at the narrowest.
 

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I have about 8mm of clearance from the XTR crankarms to the linkage and it has a 170mm Q factor so with 163mm Q factor it should be about 4-5mm.

The new XTR and XT front derailleur have enough limit adjust on the high set screw but they won't go below the granny ring position for a 50mm chainline, so if you're running a dual chainring on the granny/middle positions with a 47.5mm or 45mm chainline you might have to scrounge up a 960 series XTR to get a clean shift to the inner chainring.

What cranks are you using and what size rings?
 

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It looks like it's maintaining the 50mm chainline as the inner and outer ring are sitting in the space either side of the middle ring of a standard 3 ring crankset while using a Shimano compatible external BB bearing set. On a 2 ring crank the chainline is centered on the spot half way between the inner and outer ring.

There should be more than enough H/L limit adjust range on a current XTR FD to prevent chain overshoot.

If your heel rotates inward when you pedal, low Q factor cranks will scuff badly from heel strike (the XTR are already bad for that), and you're also likely to get the occasional heel strike on the carbon swingarm on the ETSX if you have longer feet.
 

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