I've only read the first page on this thread, but my 2c would be this.
1. It would not be that hard to code a save feature for this, a properly designed save game format would not even break current savegames. (IE people can make it themselves, without breaking current savegames provided the save format supports expansion)
2. As said in an above post, there is no need to save. Simply pausing the game and minimising, then hibernating, works fine.
If you need to save and go back to a specific point.... Why?
If you lose, you lose. Go back to your base and hire some new soldiers and fit them out with new equipment. Problem solved.
I have only ever lost a battle once (I've only been playing a week, things may change
), it was on hard difficulty and I entered the battle with a 4 man team (out of soldiers to hire). I lost miserably. But just because I lost does not mean I go back and replay it 100 times to win it, or that I want to save every 3 seconds during a battle.
Just my rant.
~evilhamburger();