I should confess: I skipped over the few pages of mechanics. Feats, prestige classes, etc. I also only skimmed the mechanical gray boxes in text.
In any case, for my ongoing Freeport game, I'm going to incorporate a fair bit of Five Fingers flavor; in many cases, specific NPCs, plots and premises. The more I've tossed the two of them about together, the more of I've come to the conclusion that a fusion of them (plus any other fantasy WHoS&C--Wretched Hive of Scum & Villainy--I can manage to work in) is my best bet, rather than worrying too much about the specifics of each individual one.
So, what are some of those other fantasy WHoS&Vs that I'm working in? From literature, I've got Sanctuary of the Thieves World series, Haven of the Hawk & Fisher series (see the What I'm Reading sidebar) and of course the prototype for all of them, Fritz Leiber's Lankhmar. From gaming products, I've got obviously these two, but I'm also brushing up on some Paizo stuff; my Absalom and Katapesh sourcebooks in particular, some of the Riddleport and Korvasa material, and the new Cities of Golarion book, which I just picked up.
I can't at the moment predict what (if anything) I'll take from where, but it's nice to have a full barrel of ideas and concepts, so when I reach into the barrel because I need something, there's always something there for me to find. If nothing else, spending a few weeks steeping myself in WHoS&Viana lately has been kinda fun in its own right.