I ran DiA for our group. The entire adventure was through Roll20 due to local lockdowns during the pandemic, but in some ways it actually helped make the adventure better.
I had read through the Alexandrian Remixes as well, so I knew to limit the Devil/Demon road section and how to make it more interesting. Even still, after the 3rd "get me this in order to get that", the players were ready to mutiny. So instead of the 5 or 6 quests, it was 4.
The real plot twist - once the players discovered that the war machines ran on soul coins, they collectively decided to destroy any war machines they encounter. It put them at a serious disadvantage when it came to combat and travel time, but I made up for it by introducing the traveling caravan earlier on. One sold soul later and the party had a flying carpet.
I also did not like the idea of Lulu. Instead, one player wanted a ring of Mind Shielding. So, random treasure granted and look! it just happens to contain the soul of the hollyphant, trapped all these years! The player would receive whispers from me and she would choose what information she wanted to reveal to the party. But the way she roleplayed her character, the rest of the party was convinced she was a split personality and she never bothered to try and correct them. Lulu actually turned out to be one of the best aspects of that adventure for our group!
Overall our group thoroughly enjoyed it. One player sold his soul for power and was turned into a spined devil at the end. The rest of the party saved Zariel and managed to return Elturel to the Realms. The paladin "fell", but redeemed herself in the end. The cleric was estatic when she finally freed Lulu from the ring and helped restore her physical body. And the bard worked hard to become a leader of Elturel once it was returned to the Realms.