A few thoughts....
My greatest concern with sins is its lack of true depth. Depth is by far the most important factor (IMO) when playing a 4x game. Its not about pretty graphics, but about options. It's about making the player feel like they are truly the one in charge. After an hour or so of sins it seems like all im doing is system hopping. Yeah I'm working up the tech tree slowly but surely, but besides that it gets a bit uninspiring. Alot of the games which sins will ineveitably be compared to have tons of options for players to interact with. I believe that sins prides itself on its real time engine. This engine allows people to actually play long games over the net without having to wait for schmoe 2 to hit the turn button. While there are inherent strengths in this type of engine, so to are there weaknesses. It becomes the devs responsibility to provide the player with something to do inbetween battles. In most turn based games this isnt as much of a factor because it becomes easy to skip by much of the tedium by hitting end turn. With real time you literally have to sit there and wait..and wait...and wait for something to happen. My greatest fear is that this turns out to be a sw:eaw without the pretty graphics. Or a real time sword of the stars (i.e. about nothing but the battles). 4x is about the drama. Give me the tools to create drama! SPACE OPERA FOR THE WIN!

. Besides diplomacy, what other systems can you guys think of?
. Sins looks like its going to be a great game when the devs get done with it, and hopefully the blend of RTS and 4X genres will create a hybrid with the best of both worlds rather than a game that's not good at either genre.
) the "war tax" kind of thing would make very war like players weaker so that more peaceful players would have more money and then be able to take out an expansionist warrior player. That would add an interesting dynamic. Logically it could even be explained by the rise in the military and thus the rise in the size of the military bureacracy, which would then make the government spend more money on their salaries.