I agree with the two or three blade cutting approach to a woods situation; Folder for most things (slicing or what might be termed whittling) and backup, Fixed blade for larger tasks that require more force and knife strength (light batonning, slicing, cutting larger live wood), and a folding saw for efficient cutting of normal sized wood for camp accessories, perhaps a shelter or longer stronger supports for a tarp.
Without a doubt I use a folder the most because that is what my brain is conditioned to reach for first in most any cutting situation where as many will pick up the fixed blade. In the woods, if had to choose one, it would be a 5-6" fixed blade, but folders are just so handy.
I really like using my GEC #42 traditional for outdoor use. Since I have two blades, there is a back up built into the knife design. But I tend to always carry my 111mm SAK because I like the convenience of having the tweezers, tooth pick, screw drivers and main cutting blade available. But, I don't want to due assisted cutting or splitting (batonning) with either of these unless it was a life and death situation. Of those SAK tools, I would miss the tweezers the most, so it would be very easy to carry a small SAK in you pack for just this purpose and have the GEC and larger fixed blade for real cutting.
In my experience, the folder has been all I have ever really needed unless I am playing in the woods. Even field dressing deer, the folder is all I needed, but I would prefer the fixed blade. I like the security of having the fixed blade available; so I will carry one. Yes, there is a lot of marketing hype involved with choosing woods-use tools as well as personal preference. Do what you like and feel comfortable with, but I think you're always better off having a knife with you in the woods than not.