I can tell no difference between Campagnolo Record (sq taper) of 30 yrs ago and the modern carbon equivalent.
This is probably because its hidden due to the amount of flex in these old road frames. No matter what chainset and bb unit is in there, its going to be buckling around under load. On a stiff mtb frame ht2 is noticeably stiffer.
Infact its also noticeable in another way (without going by feel)
I have noticed many times on both road and mtb upgrades that the front mech set up can be adjusted easier as theres not as much chainring movement once you take the bike on a road test. It might shift fine on the workstand but sometimes you have to wind the mech out a tiny fraction more with an older set up as its unaceptable to ride (when under load on the drive side)
With HT2 you can adjust the mech on the workstand and its more than likely it’ll be stiff enough under load to also be rideable in the big ring. No extra fraction further out to keep the customer off yer back.. its stiff enough to set up as close to the chain as possible and you can be confident that the flex wont cause you problems.
I have noticed this on new bikes that might have had the upgrade,my own bike and numerous others over the years. Then you add a stiffer frame into it all with a fat downtube grasping the bb shell. HUGE difference compared to a steel frame with a square taper setup. Its all just moving along bit by bit.