Echoes of the Past addon was just mentioned in the most recent update and it looks really cool!
My concern is this line:
"Please keep in mind that it is an advanced addition that requires some knowledge of the game and is best suited for your second or even third playthrough of the campaigns!"
I can almost guarantee that even if the game is fantastic I won't wind up playing through it a 2nd or 3rd time. So many games, so little time and all that.
I love the idea in theory but my question is whether its a worthwhile addon for the first play through? Looking at the revealed Beor card it certainly looks like all the achievements are doable although there are two there which require certain cards to be gained. Is this the reason why it should be on later playthrough? Because otherwise we will have to go out of our way to find them? I certainly don't mind if the other memories have story that hint towards where to find these trickier memories though.
See the discussion on this here: Echoes of the past expansion, worth buying? Who is going to replay a 100+ hours campaign?
Looking at the Beor card, you may also notice that it tells you to check out certain location cards. This may decrease the sense of discovery for you during your first playthrough.