Interesting thread, lots of good points being made.
my experience of wilderness living skills training and survival exercises leads me to the conclusion that there are two sort of phases to the proposed bushcraft/survival scenario. also there is the simple issue of time.
the first phase is shelter construction, this typically takes half a day to a day to get the bulk of it done. that's not non-stop working, that's with several breaks. that's tending the fire, your hungry friend, boiling water and keeping hydrated.
a bigger knife makes this
easier. yeas i can bend and cut saplings with my mora knife. i can limb them with a knife and a bat. but it's simply
easier with a knife that has enough mass to just slide down the side of a pole and limb several branches with a "tink tink tink tink" (that's the sound of branches coming off
) each sweep, rather than having to set the pole up on my shoulder set the knife on each branch, and hit it with my bat.
getting a small log down to fire board size can be easily done with a mora knife. it's just easier and faster with either an axe or a bigger knife. incidentally, i saw my first ever knife broken just by batonning the weekend just gone, and ihave tried hard to break a few. a 14 year old scout snapped a mora viking clean in half. or it might be a third.
go on a ray mears journeyman course or on a woodsmoke abo course, the teams get a small forest axe to do the big jobs. surely if all these jobs were so easily done with just a woodlore knife, why would they bother?
the problem with a big knife or axe as a chopper, is psychological. it's often easier to pick up a 6"dia log and smash it into pieces by smacking on another one. but when your only tool is a hammer, every problem starts looking like a nail. when your main tool is a chopper, you could be lured into doing unnecessary work.
if you've only got a very small knife, or no knife at all, you can survive, but you need to modify your expectations. you're unlikely to be able to build a full on northwoods leanto with a roaring long log fire. you'll probably shivering as you dry out the leaves in your debris hut. if you can get a fire going, you can still build a thermal kennel with just breakable branches.
after the first day or so of your stay, that shelter is satisifactorily done. but you keep improving it bit by bit. then you'll be wanting to manufacture trap triggers and fish hooks and the like. the detail work is much more easily done with a small knife. as is cleaning small game and fish.
a survival knife is one that you will always have about your person. to my mind this effectively excludes big bowies and machetes and hatchets and axes. if it's more likely to be in your rucksack than in your pocket on your belt, it doesn't count.
Ultimately it matters not a jot what your knife is, or what your particular system is, as long as you know how to use it. there is no such thing as wrong or right, just what works for you. after all, we can set a chav loose in the woods with a skookum, or an AW woodlore, or a tom brown tracker. the main question how much mess will he make before he shuffles off.
pick which ever knife you fancy designed by whichever bushcraft or survival guru you like. that knife cannot replace basic skills.
so what is your knife good at? why do you go for that one?
cheers, and.
never bone dry baked to a crisp, and never so cold that the soil freezes below an inch or so down for a couple of days. The woodlands around me are rich in biodiversity, temperate and mostly deciduous. Miles of hedges too. 
. Other items took priority, a heavy knife was simply out of the question. If I was to do this trip now I would outfit myself differently because my interests have evolved, if you will.
