I must say that I have been finding this topic extremely interesting. I have been doing draw boring thus far in the style of TIMBEAL, with the heavily tapered peg. I did this because it's what one sees really often with modern draw boring, identified by the space where the peg does not fill the back of the hole.
I had noticed when I have worked on old barns, as was pointed out earlier, that none of those pegs had a heavy taper, just the heavy taper on the last inch or so. Not having a very universal overview of old pegs I just assumed that they were outside the norm.
I really do like the concept of the full sized peg fully engaged in the peg hole, with any adjustment needed made in the tenon hole. That to me, just seems to be a more elegant solution. I'm sure that the draw boring that I have done up to now is adequate in function...but perhaps not ideal.
In view of this thread and the original question, it really seems to me that the heavily tapered peg would lose a significant amount of strength from loss of cross section and loss of parallel grain. The straight grain which is the whole rationale for riving pegs instead of cutting them from sawn stock. I figure that these subtle differences in practice will never make a difference in building longevity in our lifetime, but 200 or 400 years from now the cumulative effects make all the difference. There is a reason that for every ancient building still standing, there are countless others that have fallen in. It's a good reason to look to the survivors for best practice. I'm going to take a good hard look at my pegging practices, do some research, and try out some of the specific techniques that Jay has suggested.
Thanks to all who have been participating on this thread, it has made me rethink my own practice. It's good for young guys like me to see this kind of debate.

He Sean, you got it. This is what I meant by repetitive deformation in a peg, or simply "mushrooming." If you have acquired or been taught the skill, metal striking tools will surpass wood and leather by a great margin. I carve stone, as well as, wood and wooden joints. I have even carved "splayed scarf joints," in granite for foundational elements of a frame, like you would find in Asian. There is a traditional pneumatic stone hammer, (pneumatic tools have been around since the 1850's, one positive high light of the industrial revolution. Note: they are still made in Barre Vermont by the same foundry and black smiths-"Trow and Holden," if you ever contact them, ask for Randy Potter.) that with an adapter you can drive not only timber framing chisels of all types, but pegs as well.

I believe most folks should use softer/lighter wood and leather mallets for their chisels, if I have lead folks to believe other wise I am sorry. If you do not have the training, skill, technique, proper hammer, and strength, a metal striking tool used all day long to cut joints will cause you and the tools you strike harm. I have had some ambitious students try to use both my hand hammer and my pneumatic, and a few have ended up at the doctors for repetitive stress fractures. I didn't start off using a three pound hammer to strike a chisel. That took years of conditioning, practice and guidance. If you start off with a nice 16 to 26 oz Japanese hammer, you would probably be fine. Just as an odd note, stone carvers take to timber framing better than the other way around. It has often made me think that we should get all young craft folk started with stone then move them to wood.

Excellent observation, they make bronze hammers for this purpose but they do not hold up as well as a hand forged metal hammer. In some cases you can damage a chisel handle. Most of mine last several years to a decade, but my "favorites," often get used up about every 1.5 years. Then I simply make a new handle, it isn't that hard. If you work a lot and keep really sharp tools, you will wear chisels out quick. I can go through some gouges in under three years.

Also well said!!! I believe many of our ancient forbears of this craft cringe and/or laugh hysterically at our fumbling and follies. Such a simple thing as using the correct technique and tool, can make your work so much easier.

I am really glad you have taken something away from this discussion. It is all about the handing down of linage knowledge and rediscovery of what has been almost been lost.

This corner is getting cramped. The vast majority of my pegs are not heavily tapered. Yes, they taper heavily for the first 1/3 of the peg the other 2/3 has a slight taper. They are unlike the spruce full one inch pegs found in most of the historic fabric of my surroundings. The "odd" aspect is how come I don't use the old style pegs I find in the local building, I not saying they were odd, I am odd. Also note in my video at around 2:20 you can see what my pegs look like and how they are shaped and to what extent the taper is present, and note C's comment "thats not very tapered".

I have no fear about my pegging, tradition or not, I am setting a tradition. The down fall of my structures will be water, I know this to be fact.

I use a very light wooden hammer for chisel work, which I try to keep to a minimum, actually the corner chisel is my most struck implement. On some tough stuff, knots or bad grain I will tap a chisel. The slick is far more efficient in most cases and the axe and adze in others. I don't strike with the back of my axe, as a practice, it has happened, though.

When it comes to driving pegs, I use what is at hand, huge 10" commander, my light finish hammer, small sledge, bigger sledge, the odd piece of blocking, I don't recall if I have taken to rocks that I recall.

TIMBEAL, sorry for cramping the corner. I can't and shouldn't make generalizations about your work, since I have never even seen it in person. I didn't mean that in a personal way, just trying to make a description of pegging style.
In one way or another we're all creating tradition. Tradition is never static and it's never monolithic.