Personally I think it's simply nice that someone with a great collection takes the time to make a video, give his views, and share.
I really enjoy seeing Mark's guns, up close in detail. Especially that T&C stock is just unbelievable. DT Fletcher thought this must have been a salesman sample.
I have a Super Grade Model A and a T&C 107. Both are great guns.
The SG is better made. Both are nice to shoot and accurate. The SG is more powerful (I have been working on my inlet seal, and it seems to work well now: 15.5 ft/lbs on 8 pumps).
The T&C is easier to reseal.
The price difference was substantial, with the T&C being about half the price in 1949.
But this shows in the better quality materials, tighter tolerances, and attention to detail of the SG.