I've been looking at this myself, and also am down to the wire. I am further limited by wanting an offset drain. It would help if I could just decide on either stainless or granite, for a start! I've been considering the Blanco Stellar super single, WaterCreation ssu3018A, and the Elkay granite ELGS3019 (not sure if it could squeak in). I measured the interior width of my 30" cabinet which =28.5". So I figure that any sink that shows the actual basin width to be less than that will fit. I am thinking that the interior basin width plus about 1/4" (for the thickness of the basin wall) would be about right? I can have the lip/flanges sit on the cabinet, but since the dishwasher will be right next to the sink cab, I wonder if it will be a problem to have that lip extend a bit into the dishwasher's space (more than 3/4"). Not a problem on the other side, the flange can extend onto the top of the next cabinet's wall. But, for a 25" sink, the ones with the largest interior dimensions are: again, Blanco Stellar medium (23") Acero SS (23" and includes grate and drain), Ruvati (also comes with grate and drain, 22"), Ukinox (22") and for granite -- Elkay (22 3/8), Silgranit II Diamond (22")

I wonder how you can get a plumber to use a HUSH if he's not familiar with it? Put in writing the specifications of the work required during the bid process and have a contract. You are the consumer and are paying for the service you want done, not what the contractor feels like doing. To make yourself more comfortable, print off documentation/specs and have an itemized listing of the required work that you hand to the contractor that you are asking for estimates. If they refuse to perform the work you require, or aren't willing to research a valid process, practice, or product, you don't want to hire them. I've worked with contractors my entire life and they have a difficult time arguing with knowledge and facts.

"When you sandwich the sink rim between the heavy counter material and the cabinet side there's zero extra space if the cabinet side tops are all installed level. No possiblity of any space opening in the future.." Good theory, little real-world relevance. First, the sink flange would have to be rabbeted into the cabinet tops perfectly flush. Secondly, tops aren't the exact same thickness throughout and nearly all have to be shimmed somewhat. That means there will be a gap the thickness of the shims between the sink flange and stone bottom. That means an uneven silicone joint and on the recommended slight positive reveal that won't look good. When a sink is pushed against a stone bottom by straps, the gap is tight and consistent no matter what the shims are doing. Furthermore, if the sink ever has to be replaced, it's now much more difficult because the cabinet sides have to be unzipped to get the sink out and reinstalled to get the new sink in. A strapped sink is replaced in little over an hour by backing off two bolts. Using cabinet tops to support sinks is not good practice.

Frank has a good point. You should be able to fit a 24" sink in a 24" sink base - that's only about 2" narrower than what you are planning. Options: 24" sink base + 12" cabinet 30" sink base and 6" filler pullout "Hack" a 30" IKEA sink base to reduce its size to 27" and 9" filler pullout (one example: https://rev-a-shelf.com/2427?) IKEA Hacks: https://www.houzz.com/discussions/4306128/ikea-hacks-compilation-of-ikea-hacks Rev-A-Shelf Base Filler Pullouts range in size from 3" to 9": https://www.rev-a-shelf.com/all-products?cat=25&primary_keyword=220813 How large is your family and how much trash to you accumulate in one day? A smaller bin that holds one or two days of trash should fit under a sink in a 30" sink base. I don't know, though, about a 24" if you also have an instant-hot and a garbage disposal, even a "Compact" GD. How much space should you have in the Prep Zone - usually the non-DW side of the sink and the counter space b/w the sink and range/cooktop? At least 36" with more better if you can fit it. As far as b/w the sink and refrigerator, the main sink should have at least 24" on one side of the sink and 18" on the other side of the sink.