If you convert to a Schlumpf (speed drive), the original gear ratio will be gone.
Due to the use of a 80 teeth beltwheel (instead of 100) there will be a higher and a lower ratio.
The EVO is using a 100 teeth beltwheel, the middle gear of the EVO is equal to the single speed ratio.
Yes, I do think so, anyway the EVO will be cheaper than an upgraded LT/SX.
Did you already talk to your dealer?
Maybe he is able to help you?