Thank you all for your comments.
1) Hadrian, when will the next Version be realeased btw? I keep checking your website but it is still the old Version...
2) That's funny, cause I kind of like the Pacean. I was thinking of the population/leader picture of the House of Aleksander, for example, which seems 'out of context'.
3) I'm not really concerned about the power of the machine gun. My concern was when the AI uses them extensively. A fleet of 25 BCs with 50 some machine guns each for example, is a nightmare in a tactic combat. Literally, I can go cook my dinner when it is the AI's turn, even with fast movement option switched on. Even strategic combats take much longer to resolve. This spoils the game.
4) I understand the logic of the 50% rule, and I think although it is sometimes a pain, it is the best possible solution given the current design of the game. Again, my biggest concern was in the Ultimate Mod. Why are some captured enemy ships SO cheap to maintain: 241/0/0 for a BC? This must be a bug??? Unless they can be analyzed for tech, these ships are only good for scrapping, and then only give a very meager amount of resources...
5) I guess retroseries are fine after all: you get what you want, fast and all, but you pay for it. Sounds good. I wish the 50% rule would be clearer though: is it 50% of the original cost? If for example design1 costs 100, what is the maximum cost of design2? 150? It doesn't seem to work that way, and each time I end up finding design2 by trial and error.
6) On game challenge: the idea of having AIs surrender to each other is interesting. I wish they would do this without me having to tell them. However, before that, I wish there was a way to prevent the AI from doing stupid things, like:
- sending ships into known minefields without minesweepers;
- sending unprotected colony ships into my territory: if I can't capture them, I let them pass, and then follow them with a loaded troop transport

This is cool early in the game especially if the enemy can colonize planets that I cannot. Plus I get population that usually breathes something else...
- sending tons of ships into black holes
- destroying colonies instead of invading them with troops (even colonies I just took from them, so they kill their own race...)
- not using master computers to counter allegiance subverters... Btw, I think the self-destruct component should have a chance to work against allegiance subverters (is this possible to implement?)
- etc.