It seems to me that a jointer is a once-in-a-lifetime purchase. When I look back at tools I have bought before, I often wonder why I didn't buy better quality or bigger equipment from the beginning. Therefore, now that I am looking at buying a jointer, I feel tempted to go for an 8" machine rather than smaller.
On the other hand, I do wonder if it will be more than I would ever use. It seems also that if you make a mistake and hit a nail, those 8" knives will be worth a lot more to replace. With this being a small market tool, resale value of a bigger device would probably not match up as will with purchase price. Certainly you pay lots more for the extra couple of inches. I don't yet have any significant hands-on experience and therefore would definitely be a newbie to that tool.
Any ideas out there? Can you do almost as much on a 6" machine as an 8"?
Dave