Hi!
I'm just finishing a GC-1 game, and can tell you there are some quite unpleasant things in it. The main one is I can't stop spending money on a planet that has built everything I deemed needed there. So its high production only wastes my precious money, and if I keep it producing high-maintenance improvements, its maintenance costs will rise skyhigh, and eat even more of my precious money, while the rest of my planets will still be struggling with production of some semi-advanced improvements.
Another gripe with GC-1 is tech trading. In early game everybody has everything. OFC at penultimate intelligence of the AI I'm excluded off that trade. In mid-game good civs don't trade with evil ones, so that tech-sharing diminishes somewhat.
I have also a nasty bug: for morale and econ it works only what I build directly on a particular planet. Starbases and "wonders" don't.
I'm running my empire now at 55% spending, but everything I build costs maintenance. I can stop building ships and buildings, but then my research makes a 500BC hole, and I need to decrease spending to about 40% to stay positive.
In GC-1 gameplay is slower, invasions cost A LOT of money, AIs attack you even if they lose lots of money from trade, you can't zoom-out, and tech tree is a mess, not a tree (I'm lost in it after not playing the game for just two years).
OTOH there's no magic bullet in form of a rock-paper-scissors weapons and defenses. That's good (you can't wipe out significantly more advanced ships with less advanced but properly tailored defenses and weapons) an bad (when opponent puts in orbit a fregate, it's attack over for any earlier ship model (battleaxes, corvettes...). Even attition doesn't work, since you can't move ships there fast enough). AIs aren't so sensitive to trade and diplomacy (you can't avoid wars just by diplo and trade). Since pop grows slowly, and ships travel slowly, wars take quite a long time to unfold (no blitzkrieg until late game). Morale decisions arise through the whole game, there's only one starbase that holds all modules, money from trade really matters, and most importantly,
it runs on my old portable.
BR, Iztok
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I'm running my empire now at 55% spending, but everything I build costs maintenance. I can stop building ships and buildings, but then my research makes a 500BC hole, and I need to decrease spending to about 40% to stay positive. 
