Hello, My Friends!
For a very long time I have in mind to ask for that option, especially now when We are comming to Mutated Expeditions. There are at least 9 unique armor sets within game atm (before patch) which are pretty much worth to look on:
Avenging: Avenging Head Cage - Item - New World Database
Augur: Cowl of the Augur - Item - New World Database
Archmage: Shadow Work Boots of the Archmage - Item - New World Database
Corrupted Rage (Gloves are not possible to obtain yet): Vambrace of Corrupted Rage - Item - New World Database
Fearless Spy:Fearless Spy’s Jacket - Item - New World Database
Highwayman: Highwayman’s Boots - Item - New World Database
- 3 Harbinger Sets:
which are already possible to upgrade/obtain around 600GS from drops.
Problem with first six sets of these armours is that they are possible to obtain in low 60+ elite zones, there is no way to get for example Fearless Spy’s Boots with 590-600 Gear Score, beacuse of Mangled Pox Gate area level restriction (which is 500-520 gs drops) which also means that there is no possibility to upgrade them by Umbral Shards. Sadly at the moment its dead content.
I’ve spent myself 2.5 month to obtaint all Harbinger sets, but still few parts of them are 589GS, and even with new Umbral Shard mechanic I cannot upgrade them…
I would love to hear your opinion about it. Maybe its not much, But I consider it pretty epic to obtain rare pieces of gear + its some tiny bit more content to do, maybe new goal for people like me who like to farm mobs for many hours 
GL with Mutations!
-Adamigo