Before buying a gas auger, I used both the Finbore III 4.5 and 8 inch augers. The smaller auger cuts faster than a gas powered auger, but the hole is small, only good for perch and other pannies. The 8 inch auger was great when it was brand new. Once I had to replace the blades, I could never get it to cut the same way. Once the perfect angle of the blade is gone, its tough to cut with. by the end, the auger would only spin on the ice...impossible to cut with.
To answer your question, the curved blades of the Fin III are supposed to make cutting more effective. I would say stay away from any 8 inch manual.
Tam bo