I wouldn't assume stainless steel sink. You don't like the cast iron cause of chipping and staining, but how do you feel about water marks, scratching and dull haze which are par-for-the-course for stainless. Have you considered Blanco Silgranit? IMHO, Silgranit is the greatest thing (as far as sinks are concerned) since sliced bread. No chipping, scratching or staining, can stand temps up to 536 degrees, They come in undermount or drop-in styles, and some of the sinks Blanco categorizes as undermount can also be installed as a drop-in (you have to check the website specs). What size sink are you looking for? If you want the "cool contemporary" look, get a single-bowl rectangular Silgranit sink in the anthracite (black) color. Not only does it not show any stains or grime, but the black is way-cool. Silgranit is also offered in White and Biscuit and several other colors if you don't want black. We chose the Silgranit Super Single in anthracite, and sometimes I have to remind myself to clean it, cause it always looks great. The sink will also fit just about anything.

I have almost NO room at all under mine. The garbage disposal just about fills it. In fact, if you look closely on the left door you can see the black marks were it rubs against the inside of the door. The GC had to rout out some relief to get the door to close completely. I also had to carefully wrap all the hanging cords around the drain pipe to clear a bit of storage space above the pipe for the fertilizer and watering bottle for my plants. Still, I got the sink and the look I wanted that has the sink sitting forward, seemingly on the legs (that's what brought the disposal up against the door). Think about what you want under there. I could have gotten a smaller disposer (I compost so use it infrequently). And I don't use a lot of cleaners. I also don't have things under there like instant hot water or a soap dispenser -- just the guts of an airswitch. If you want those things think about where they'll all go. All in all I'm very happy with the look and the storage works for me. But you should be aware going in that it's sparce!

Facts are, no sink cabinet is really needed to install an apron/farmhouse sink. As long as there are adjoining cabinets on both sides, the necessary support structure can be attached to them. If one side panel of your present sink cabinet is damaged, a carpenter could make a new plywood side and attach it, and it could provide the needed support for the apron sink's substructure. AFAIK, copper sinks are a little lighter than the fireclay ones, and certainly lighter than the cast iron examples. Casey

Rachiele makes one in copper or stainless, and they will do custom sizes (see link). They have a patent, but I honestly don't know what makes it so different than other options. Also, Kohler has this option on their Whitehaven (enameled cast iron) and Vault (stainless) 7" apron front sinks, but I'm not sure if their sizes would work for you. There may be other options, but those three definitely exist. Here is a link that might be useful: Rachiele apron for existing cabinets