As far as the speed comment goes, yes it's noticeable, even getting off the lift if you've ridden an old board for awhile you'll feel a difference. I remember getting the K2 Wisdom (one of my favorite boards ever) a long while back and it was a holy shit moment in terms of the base coming from a cheaper plain ptex base. Even after 16 years or so of riding, the first thing I noticed on the slopes with my X8 was the glide of it while it had only been 3 years or so since the last stick. Hell, I use the same board for park as I do boarderx.
A lot of times people will have more confidence on a newer, high end board than on their old stick and that goes a long way in terms of learning. That specifically is all mental, but it can make a world of difference. Yes a newer board will hold an edge better, have better pop and probably be lighter as well. Camber hasn't been brought up in this thread yet, but you will immediately notice a difference in buttering and flex with reverse camber, rocker, whatever tech slang a company uses.