In looking at the instruction manuals for the two models at the Miele website, their steam ovens are described as steam only. The cooking temperature for most foods is 212, with sausage and some fish at 185. I didn't see anything that had a higher cooking temp . The manual also says "The food will not brown and does not get a crust. The food is gently steamed, not fried or baked. Cheese will melt but not brown." In comparison, the Gaggenau has a temp range of 85 to 450. I've cooked things such as meatloaf, baby back ribs and roast chicken at 400 with 100% moisture and gotten a browned, crisp outside. At those higher temps, the oven is roasting but with moisture that keeps the food interior tender and moist. It's not steaming at higher temps. And there are obviously a lot of combinations of temperatures (85 to 450) and moisture (0%, 30%, 60%, 80%, 100%.) As for the drain, it has a cover and all that goes down it is water that is injected to condense steam before opening the door. There's far more stuff that goes down a kitchen drain.

We have last year's 27" Gagg combi & love it. (It's identical to the 24" inside.) Having it plumbed is fantastic. It never runs out of water/steam, it can remove the steam before you open the door, we never have to deal with removing water, and the capacity is larger than an unplumbed steam oven. There is a water hardness setting that you must set before using the oven the first time. You'll also want the water connection to be easily accessible in case you need to clear the filter screen (which we haven't had to do yet). Our water shut-off is in the rear of the cabinet above the combi, and our carpenter built a removable cover that sits in front of it. I can still use the cabinet for the combi racks, trays, muffin pans, etc. in off-the-shelf tray racks. The combi can also be used as a regular small convection oven for casseroles, baked items, & so on by setting zero steam & oven temperature. The ability to combine 60% steam with a temperature of 250 allows for gentle reheating or 360 to roast chicken while keeping it moist. A friend of mine has her 24" aluminum Gagg combi stacked over a 30" SS Miele Masterchef oven & it looks great. We have our combi over a Gagg convection oven, but we mixed up the rest of our appliances, including a DCS all gas range & Monogram Advantium.

Yes, 6805 has a drain line. Miele non plumb (6800 for example) has two containers, waste/condensate container and fresh container. For 6805, there is only fresh water reservoir. Plumbing takes care of filling the reservoir automatically, as well as draining out all the waste. In descaling program, descaling tablets must be dissolved in the reservoir manually. Half way through the program, small amount of left over solution must be emptied out manually before the machine refill the reservoir with fresh water and rinse itself. Emptying the reservoir after each use is mainly for limescale prevention per manual. I have soft water so don't follow Miele's instruction of emptying to after every use.

Why would a plumbed version be any more of a problem when it breaks than a non-plumbed? Worst case if you replace a plumbed with a non-plumbed then just cap the supply & drain tubes. A non-plumbed has a pump to go bad and that is also the part most likely to fail. Plumbed uses house water pressure in place of the pump so is less likely to need repair to begin with. I can't understand $1500 for the plumbing except huge profit for the plumber & builder. When I added a coffee station in my studio it cost $700 and that was a 60' run for both supply & drain and included plumbing for both a sink and an espresso machine (Breville Touch). Are you sure they didn't say $150?