For SOZ no ivory and 300 shields looks OK (would we still built it at those rates? - that's little better than 3% per turn if you value the AC at 50 shields)
With regards to civassist II, I play with it all the time, it does reveal some information that wouldn't be available direct from the multiplayer game (number of cities, which technologies and resources are available from the opponents, how much gold they have). The difference comes from the fact that in multiplayer you don't see the other people's half of the trade screen. The choice comes down to flavour, do we want it to seem more like a multiplayer with mystery surrounding the trading, or a more analytical game closer to the single player version. I prefer analysis (and would have to keep reminding myself not to use it) so I vote yes, but I do understand the reasons for not allowing it.