Hi Adam, yes it is a good debate, however it is one I have had many times with people.
Lets address each issue again.
String theory.
This just doesn't carry at all, yes I know how big the nock slots in the arrows were (1/8") and I know what materials were used, however there are no surviving strings of the period and the knowledge of how to make them is lost to us, but one thing that you can be absolutely sure of is the string fellows of the day would not be making strings that broke after a few arrows...there would be little point and the Warbow would be pretty useless if the archers could not rely on their strings.
Diminishing returns.
Tests have been done using self yew bows of differing draw weights to see what weight bow is needed to get a battle shaft the minimum practice distance of the day (220yds) This is the distance between the "Butts". Now the arrow would weigh in the region of 75grams, now just to make the 220yd distance you need a bow of 120lb minimum, that would be shot at an elevation of 45deg, so not an aimed shot, now take into consideration that the target they would be practising at was a garland of about 10" diameter, this needs to be an aimed shot, so a much flatter trajectory was used and obviously a much more powerful bow would have to be used to do this.
A very heavy bow may not send an arrow that much further than a bow which is lighter, however what it can do is send a much heavier arrow to the target and as such a heavier arrow has much more hitting power.
Weapons that made Britain.
Mark is one of my closest friends and let me tell you that he was very unhappy with the program as they changed a great deal of what he did to coincide with a prior agenda they had, this was done after he had left, he has also said that if he had known what the producer had in mind, he would never have got involved. The air cannon test is a sham, as the head type used was not a plate cutting head but a long type 7 (needle bodkin) which were used against chain mail, not plate armour, also the paradox of the arrow is completely lost when using the air canon, this is the way the arrow reacts as it travels around the bow, giving much more power in the arrow.
The MR bows.
These bows are incredible and are made from High Altitude Alpine Yew, Probably Italian, This wood is not like any yew that you may be familiar with, I have made more replicas of these bows than probably anyone and from the correct wood, even when using the worst piece of yew with very low density 30 rpi, the weight still hits 130#+ and even then the bows I make are at least 2" longer, so shorten them by 2" and you will be at the 150#+, Now if you take a similar density piece of wood 60+rpi the weight increases massively. This is the defining point, The bows are there and all measurements can be taken and if the correct wood is used to replicate them you will see the draw weight, regardless of what you or anyone else may think, this is fact.
This is not about chest thumping as you put it, this is the reality of it. Archers of the day were not like the archers you see around today, these were the best, they had trained since the age of 6yrs old and spent their life training, the military archers were the best there was and were chosen from around England and Wales for their skill by having competitions and only the best were taken as military archers, Now think of the MR, this was Henry VIII flag ship and you can bet your life that as an avid archer himself, the archers on board his ship were the best of the best.
You need to get out of this mind set of looking at archers today and comparing them with the archers of the medieval period, there is no comparison, Mark Stretton has shot a 200# bow and I'm sure he won't mind me saying it really did hurt, Another friend of mine, a young lad of 23 managed to draw back a 202lb bow to 29", There is also a young Welsh lad who is shooting 140lb bows and is only 15yrs old, My own son is just turned 10 and is shooting 55lb bows, these are just recreational archers, as are all archers nowadays, their lives do not depend on them shooting bows, however the medieval archer had a reason to excel and become a military archer as it was a good way of getting them out of the poor villages and a chance to become quite wealthy.
Any way That will do for now.
Cheers
Steve