The white color has been discontinued replaced with Dune. The lighter enamel interior is actually a sand color. The black enamel is better for high temp cooking so it's used on their frypans, grill pans and woks. It's better for that purpose. It's definitely not inferior, just better suited for the job. The only line that has the black enamel on all the pieces in the black matte or satin black. The advantage is the black will season with use, and doesn't show staining as the sand enamel will over time.

I have a white Irontones sink, undermounted. No scratches so far, I do have the Kohler grid in it. I had another Kohler cast iron sink in the kitchen before the reno, I love cast iron. I did consider a Silgranit, but couldn't find a white one to see in person, so I chickened out. The only picture I have handy is just after installation, before the strainer was even installed.

You can cut off and cap the copper pipes coming out of the floor, but I'd first try to figure out where they are coming from. You don't someone turning a shutoff in the basement or crawl space (I wonder what this does?) and finding out it controls the water line running to this pipe. Smaller sizes of cast iron pipe usually have threaded fittings, while large waste pipes may use oakum and lead for the seal. Old cast iron pipes are usually fine for vertical runs (vent stacks, etc.), but horizontal iron pipe runs trap moisture and form rust in the bottom (looks like stalagmites). This rust catches on whatever is draining through the pipe (hair, soap, etc.) and creates a blockage over time. A plumbers snake becomes your friend. The rubber fittings are usually called Fernco couplings, since its the most common manufacturer of this type of coupler. They are used to connect dissimilar pipes during renovation (iron pipe to PVC, etc.), or to reconnect a pipe that has been cut. There is nothing wrong with using them if the pipe is adequately supported on both sides of the rubber coupling. Bruce

Back to OP's question--cast aluminum vs cast iron. I did own a 5 qt Club cast aluminum DO back in the day. (Raw metal interior/ painted exterior) Back before I became a pressure cooker convert. Used it quite a lot because it was the largest pot I owned. But almost exclusively as a stove top pan....I have never used the oven for much other than baking & Thanksgiving turkey & stuffing. Probably because I lived in the southwest US for many of those years. And in a house without air conditioning for some. So, climate was a huge influence on how & what I cook. Aluminum (and copper) excel as a heat conductor and is quickly responsive to changes in the burner output. Cast iron is superior with retaining heat. Which makes CI theoretically better for low, slow cooking. Raw aluminum & raw cast iron don't like acid. So we have enameled CI and non stick aluminum available that are resistant to acidic foods. Each have their place & best uses. You can have both or choose one that best suits how & what you cook the majority of the time. Personally, I don't have much use for a DO. The pressure cooker handles 'low-slow' food at warp speed and on a whim "I need refritos to go with the enchiladas..." The large stainless stock pot handles big batches of canning tomatoes and large batches of broth on a winter day (smaller batches are made in the pressure cooker). I do have a couple or three stainless DO's of various sizes (I haunt garage sales) but those are seldom used anymore--empty nest. That said, I 'would' use my Le Crueset for No Knead bread (which is wonderful). Except that I am gluten intolerant. So bread is mostly off the menu for me.