Here's a little review I did over on CanadianGunNutz.com on the topic of augers
i have an 8" Finn-bore...love it I've got 3 seasons on the original blades and they're still going strong (although Im going to change them anyways this year). They're no 6" as far as ease of drilling goes, but when you have anything over 4lbs looking to come out of the hole you'll be glad you carried the 8" .
I found I can knock through 12" of ice in a minute-ish , mind you thats after you use them for a few weeks and get the muscle memory back . My walleye trip yesterday I managed to punch through 7" in 40ish seconds