As Malcolm said already, Berto's book states that both the XC-9000 and XC-Sport 7000 are able to handle a 34T sprocket. It also states that both are indexed compatible. FYI...In his tests, Berto used a 6 speed, 13-15-18-22-26-32 freewheel for the touring derailleurs.
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Ese dicho que me han dicho que tú has dicho que yo he dicho, ese dicho no lo he dicho, porque si lo hubiera dicho, ese dicho estaría bien dicho por haberlo dicho yo.