One thing to consider is that with myth drannor it's 4-5 rare items per end chest, so even if you have a 5% chance to hit the rare drop table out of the 34-43% chance to get a named item, that's only a 1% - 1.2% chance to get a specific item (assuming all rares have the same chance)
Meanwhile Lammordia rares are a 6% chance to hit the table and 3 items on said table (and thankfully not artifacts this time) so precluding you hit the named item drops you've got a 2% chance to get a specific item. That's a pretty big difference relatively but the real question is however whether it is enough.
However the rares in this pack's main difference is they have one more pack augment slot and one less innate effect, so the question of this expansion when it comes to rares is mostly what are the default effects on the rare items and how much the crafting is better than default effects as to whether the rares really end up as chase items.