Most of the rules he (they) have been hesitant to follow are (some of these may have been played wrong even in the 80's & 90's):
Monk and warhorse (stating quota only)
Get sent to a new space after losing a battle and ending the turn
no unfinished quests in the inner region (tho we allowed it yesterday because we played with a different inner region)
leaving the CoC
and a few other smaller rules that I can't remember
I would say it slowed it down a little. We played 10/1/2 hours with 3 people, but we have had long games before, many of them, and we don't mind. I think I would have leveled much faster if the enemies had not been cut down, but it ran evenly since there weren't lots of higher level monsters either, and we definitely saw cards we never played before!
He also now agrees with me about day/night too! He will be removing it from play. He also wants to remove both the werewolf and the Reaper. I play with the Reaper, but not the werewolf. He thinks these 3 things slow the game down, and I agree. But using just the reaper is fine with me, its fun, even tho it gacked me last nite badly!
I don't play Talisman seriously, I am there to have fun, and if I get toaded or Reapered, I don't mind.
In our last big game, 5 players I think, I showed them all the combination of the Reaper and the roll only 1 card, as an example of some cards being too powerful which I learned here. I will never play that combo again, its just too mean.
He likes to keep the cards, but thinks the Reaper is the criminal here. :-)
he is like level 17 in the DE version, so has been playing a lot of official rules. None of his games are online only against the PC.