The biggest gains from these motor are from the intake side, you try & run fast with a big sock rolled up in your mouth.
You can compare a KTM big bore short stroke quick revving motor to a long stoke motor, the shorter stroke will always rev quicker if both bikes are standard, but there is some thing you can do to a XT, if you had to ride Kriss007 XT it would smash any KTM 690 by a long way with 76 rear wheel HP.