ellessebee -- your salesman sounds like, well - a waste of space.
I have a Miele combination oven, the low end one. I can tell you about that. There is a higher end one; I can never remember their names. Maybe "speed chef"?
The difference, I think, between low and high ends is the high end has a mess of preset cooking combos. My low end does not. It has three cooking methods and all combinations (and permutations) of these are available. They are (1) MW (2) convention oven (3) broiler. They each work great by themselves and well together too. But there is a long learning curve, I find, in figuring out what to do, how to cook the food. I find, like others, I rarely use the "speed" setting because, in part, it's not necessary. Being a small oven, it's really efficient in there -- it holds my huge le creuset lasgana pan just fine but takes about 3 minutes to heat to 400. Cooking stuff on just regular convection is way faster in there than in my oven. I use it as a "second" oven preferentially all the time!
I love the thing. The broiler works great. The MW is not quite as even as I'd like -- there's no carousel of course and sometimes it's not the evennest of MW-distributors.
I love that it's electric and I can program it to have dinner cooked for me when I get home. I love that!!!! (I know, not exotic but I've never had it before).
Mine is 240V; I read that if you want to do this combo thing, it works much better to do it with the huge burst of power. Know that this takes a dedicated 240V plug, so more costly installation, perhaps.
I bought this over the Advantium because I wanted it undercounter. The Advantium, all agree, really is, as advertised, not adviseable to be mounted down low -- apparently there is a scalding-steam issue and the location is a danger. There is no such problem with the Miele. I'm not quite sure why not, but, well, I can live without knowing that.
The Miele was costly, but it has become an integral part of our kitchen-life. I understand others love their advantium as well, I just couldn't make it work for me.
If you buy one of these things, do heed the advice from many on here to design a narrow cabinet immediately adjacent, either horizontal or vertical, to house the racks that will need swapping out. Without very easy landing-space, the machine quickly becomes a pia to use to its full potential and therefore morphs into a really expensive water-heating unit. You don't want to waste money like that -- do yourself a favor and front-load the planning for this thing to work as you'd wish it to. I think that also means make room for the 240V feature as well, though I'm not sure of that. This was my reading on it all at least.
BTW, I vaguely recall some discussion about that fourth heating element on the floor of the advantium which the Miele lacks being good, principally, for pizza. I can't attest to that being its only utility, but if that is the case, then for us at least, that function I would prefer in the gas oven anyway, so I don't miss it that I know of. [Actually, that function I prefer to relegate to a pizzeria who always does it way better than I can anywhere at all. For some reason I make the worst pizza on the face of the planet].
g'luck!
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Fridge / Freezer with handles on same side
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