From my experience with Venice so far, this would pretty much destroy the Civ. I've played a few games as Venice, and what really makes it work is the fact that you can send food/hammers to your capital from your puppets (which is a huge boost to your city, I ended my last game with something like 40 pop in Venice), and the fact that taking a CS will give you some early units to avoid those turn 50-75 dows for having no army.
This. I usually need one or 2 puppets so i can establish a production and food trade route.