Currently I am a Person of Some Little Importance and have unlocked all 2nd tier locations and the University and LoT. I do not have a ship, access to Mahogany Hall or the Cave of Nadir. I finally have just enough fate for some Fate-locked content and have been deciding which one to splurge on. I’m leaning towards a Trade in Souls because I’ve seen the Shepherd’s Timepice/ Spirifer’s Fork content numerous times in regular storylets. Does anyone have any recommendations for Fate-Locked Content or, more specifically, if a Trade in Souls is worth it for mid-late game, as I’m sure I’ve missed many options in the early game when it first unlocks.
Yes, it’s worth it. It permanently unlocks profitable actions on several cards, and gives an interesting look into the soul trade. If you’re a member of the house of chimes you can also use the fork/watch while pursuing the story of the regretful soldier.
If you have finished the University storyline, Flute Street is widely regarded to be one of the best pieces of Fate content, though not the most profitable. It can be unlocked after solving the case of the Glim-Sculptor.
It’s also currently the only way to grind favors: rubbery men that is neither card based nor force-draw based- well, let’s add on "and is a one-time payment." (it’s still a loop, not a single repeatable storylet- that’d be game-breakingly good grinding.)
It’s also the partial source of the best persuasive weapon in the game (you also need rubbery renown at 40, which is equivalent to 238 favors used optimally on renown, along with the associated items you spent), with the exception of the profession one. edited by Grenem on 6/20/2016
Another good story to buy, after Trade In Souls, is The Gift. That is possibly my favorite story in the game, and finally answers all your questions about the horrors beneath the palace. It also permanently unlocks a useful new card.