The clutch and gearbox gets most of the abuse from the larger drill. The 8" will be a little easier. I have the 9" and 6" drills for mine, the 6" is obviously faster and easier to pop a hole with. Depends what time of fishing you do. When the ice gets thick and there are larger fish around the 9" is nice. One thing I do like about the 9" is I can open or even drill out 8"holes cleanly with it.