Shatner
Warlord
I don't like the idea of allowing mines anywhere. They should still be limited to hills and metal resources. Flat land is still for farms, workshops and other improvements. This might result in some flat land being undeveloped in Khazad lands, but that seems fine to me. The basic idea that I had in mind was that mines are the center of dwarven life and that should be reflected by giving them increased commerce.
Shatner's idea is interesting, though I still think it should be limited to hills / metal resources (and mountains if/when that feature is implemented).
Having mines produce food as well is also interesting, but seems a bit overpowered. You would definitely need to introduce a penalty on regular farms for the Khazad but I do like the flavor of having mines be the focal point for all dwarven activity.
I guess I should make one thing clear which I just sort of snuck into my "Dwarven Settlement" idea. Farms are the meta-improvement; working farms serves no direct purpose other than to allow you to work OTHER improvements that you actually care about (mines, windmills, towns, workshops, etc.). If you make it so the Khazad get -1 food per farm then they will have a much harder time capitalizing on flat lands. Only when they research sanitation or run agrarianism can they actually get a benefit from a farm. What this SHOULD result in is the dwarves having smaller cities overall.
HOWEVER, a Dwarf Fortress is the equivalent to a really good mine (+3 hammers), a town (+4 commerce), an AG farm (+2 food) AND a castle (big defense bonus). As such, a single population point can be spent working the equivalent to three productive tiles (mine, farm, town) with the added benefit that the super-tile gives your units a defense bonus while trying to prevent it from being pillaged. So, if a single Khazad city has three of these super-improvements in it's fat cross than it is getting the equivalent benefit of working 9 tiles (and therefore, having 9 extra population points) while only needing 3. So, the dwarves can have smaller populations (which is good and thematic and cool) AND have super-duper awesome mine tiles (also good and thematic and cool) without being meaningfully stronger than the other civs, who can work tiles the old fashion way (building farms, growing their pop and sending their excess workers into the rest of their fat cross).
Now, for this idea to work (a few super improvements around a smaller than normal city) you need to allow each city to be able build three or four of those super improvements. So, you either allow them to be built anywhere or... you make the dwarves cry into their ale when they can't find a location with hills spaced exactly two tiles apart.
I agree that normal mines shouldn't give food. In fact, I think Khazad should have a hard time getting as much food as the Bannor or the Clan or whoever. So, yeah, allow the dwarves to build normal mines on hills and metal improvements like normal but also allow them to build super-mines wherever they want; they won't have the food to work most of those normal mines (unless that location has an abundance of food resources) and they won't need to.
Got the improvements in, thought I'd post a screenshot. Keep in mind, the yields shown are on a hill... A mine would have the same yield as the first improvement, minus the one commerce. The way it's set up, you have to choose... Production on a hill, or food on a flatland? You have a limited number of these, so you have to choose wisely.
That is a screenshot covered in awesome sauce. That looks really wicked AND would allow the dwarven settlements to look very different from normal mines. Also, it conveys the fact that those settlements also serve as fortifications. Bravo.