Re: difficulty levels - the nice thing about Sins is that you can set the AI level for each player. I would suggest not being masochistic and when you're ready to increase your challenge, just put 1-2 players at Unfair (or whatever).
You seem to be getting the idea that unfair is somehow too difficult for us, and that simply isn't the case...I am relaying a complaint that I have heard from players new to ICO who are trying to get better at this game -- they want to practice in SP before going into skilled MP, but there just is no good AI difficulty for that...hard is too easy while unfair is too unrealistic, and simply saying "well then just stack 2 AI's against you" only provides another unrealistic alternative...
This issue has also cropped up in unskilled ICO games where AI's are used as fillers...there simply is no good solution -- either use hards and make the game too easy, or use unfairs and the game just becomes "Sins of Starbase Spamming"...mixing up the difficulties (some hards and some unfairs) sounds like a nice idea, but in practice I have found it does not work well for FFAs or multi-team games which are common for casual MP/SP players...
If you nerf hard, you will be destroying the best difficulty level there currently is....this is the level that your casual players thrive on, the level that they eventually get up to and enjoy once they know how to play the game...it seems like you are nerfing it because it will make some number scheme look better, but your SP crowd will be deprived of a good difficulty level and will be left with picking the lesser of two evils -- either be "masochistic" and play on unfair, or stack multiple hards against you and forget about playing FFA...I really don't think that's the direction this game needs to go....