Silverionmix: I'm on a tablet, so I'll just list my counterarguments in order of the arguments they, uh, counter.
DF will have interaction with the outside world, but that doesn't mean we should screw with the interface. If it ain't broken...
Triggers: If "whenever a dwarf panics/sees an enemy" is a bad trigger, we need to scrap that idea. If we scrap it, there's no good way to get dwarves to slow time when they're in a fight wth an enemy, unless the slow-time doesn't start until the dwarf is damaged, which has several issues of its own. If time doesn't autoslow for combat, we need to make a fast-mode for combat. Having messengers force slow-mode until they reach your guards is dumb; how do you define guards, and what if you're not protected by them and rather by, say, some kind of trap/s? Can you not see issues with marking critters as unimportant at will? And why is "dwarves handle time-sensitive issues" not a good way for fast responses to happen when most things that would require them autopause the game? And of course it's vague--there's at least a thousand situations it would apply to.
Games are not about forcing you to do stuff, they're about letting you do stuff within limits. By your logic, the best game would be an awesome but non-interactive one, whic isn't really a game at all.
If tere is the slightest difference between the modes, as far as anything goes, it will be abused. It's not like "minimising haling distances improves efficiency," or even "building this complicated device improves efficiency," but "oressing this button improves efficiency."
I think that reaching the edge of the territory you control taking a week isn't too unreasonable, considering that you'd have to be pretty damn far away in DF for it to take a week. Dwarves aren't as slow as you all seem to think--a muner can dig many tiles a day, and I don't think it takes multiple days to build something in a workshop, barring huge haling distances.
And one last question: Why is the slow mode needed? Couldn't we accelerate the working and consuming speeds a la the suggested fast modes and leave out all of the issues, obvious and not, which would occur with such a fundamental change to the Fortress Mode engine?