I replaced the tiller on my M17 when the original cracked.   From West Marine I purchased a Catalina 22 tiller, and modified it. I routed out the butt area so the cheek plates would fit correctly.  It extends forward as far as possible on the M17 and just clears the main sheet.  It does help better balance the boat, but it also has a large handle area.  It also provides a better attachment point for the auto - tiller.

John