I've read through the playtest adventure "Reclaiming Blingdenstone" to see what, if anything, can be added to the OotA version of the gnome city.
In summary, what I found most useful was the addition of a "backdoor" from the Foaming Mug down into the Wormwrithings (and assorted quests), and the info on Ogremoch's Bane specifically making it more of a legendary threat.
Consider the following to be my personal notes on incorporating good stuff from Reclaiming... into Out of the Abyss. I'll take this one Reclaiming room at a time. All "areas" refer to OotA. In effect, this will make a comprehensive listing of any differences.
1-5: "Outer Blingdenstone" defenseworks.
6. Hall of Miners: Now occupied by wererats (area 25)
Ogremoch's Bane has moved to the northwest. The way you can't just attack OBs elementals is a nice touch - Ogremoch's Bane is a legendary creature and I think it's wrong that any old swords for hire can just get rid of it. (I'm using Henkala Shadowsong and the Pechs to solve the quest; the gnomes i.e. Nomi Pathshutter don't have to know, she's a novice after all)
7. Armorers and Weaponsmiths Guild: Now called Caves of Clatter (area 11)
8. Ruby in the Rough (area 8!)
Kargien's quest for the Crown. A reason to visit the imposing structure that is the House Center is nice, though the quest is arguably superseded by the Battle for Blingdenstone. Use to add intrigue to the otherwise very marysuian Daggermattocks.
9. The Steadfast Stone (area 22) already got a quest (see the Standing Stones, area 13)
10. The Trillimac Stockade (area 29)
The Orc threat is quite comprehensively replaced by the oozes, arguably for the better (since orcs is almost the archetypical generic D&D threat, although oozes isn't MUCH more interesting)
11. Silent Shrieker.
This area appears to have been removed from OotA.
12. Phantasmal Glamours, now Reception Hall (area 5)
Henkala Shadowsong (and the Pech quest) can be reused, though I'm leaning toward making her a ghost in the abandoned residential area.
13. Trader's Grotto (area 7)
One of the few areas that have been repaired in OotA over RB.
14 The Foaming Mug (area 16)
I think it's cool how there's a back entrance into town, and that it's here (let pesky adventurers take the brunt of any attack!). Adding a mission into the Wormwrithings could be a cool if dangerous "prequel" to the main OotA story.
15. The Singing Stones (area 15!)
I don't remember this area to be described as a tavern, but that makes sense: I wondered if "big folk" inn, the Foaming Mug, would be the only tavern in town: there surely must be somewhere only gnomes go.
Getting singing crystals from the Wormwrithings sounds like a cool mission.
16. Golden Hills Hearth.
This area appears to have been redesigned into area 8, called Cultivation Caves.
Since Mantol-Derith is prominently featured already in OotA, I'm quietly dropping Fendrick Pestle and his trade mission. (OotA already has two trade missions: to Gracklstugh and Neverlight Grove)
17. The House Center (now area 28)
I'll stick with the OotA version.
18. The Speaking Stones (area 13)
(Don't mix up the Speaking Stones, the Singing Stones and the Steadfast Stone!)
Since OotA already offers a quest starting here, I'll go with that.
Meaning: instead of "Waking the Speaking Stones" I'll use "Cleanse the Steadfast Stone"
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Here are the reinterpreted chapters of Reclaiming Blingdenstone:
Chapter 1: Get the pech's aid against the elementals
Makes Ogremoch's Bane a legendary threat, which I like.
Chapter 2: Close off the Wormwrithings and collect singing stones
Added
Chapter 3: Retrieve the crown
This can be kept.
Chapter 4: Wake the Speaking Stones
Replaced by a version of Cleanse the Steadfast Stone that makes Ogremoch's Bane a more legendary threat
Chapter 5: Stop the raiding orcs
The orcs are comprehensively replaced by the oozes, as well as the medusa.
Chapter 6: Negotiate Trade
Use the suggested trade missions to Gracklestugh or Neverlight Grove
