Some of my old high school group and I are headed down for our friends lakehouse this August. We have a tradition (started with TI 1!) of always playing Twilight Imperium when we are down there together. This will be our first trip since TI3 came out, so I'm looking forward to getting a great 6 player game in.
I've only played the game a bit so far, but from what I've seen that ISC works okay as long as everyone understands how important it is and if everyone understands that the game generally plays better if more focus is put into bringing down the leader.