First of all, left-over food does not taste as good after MW-ing compared to warming it up on the stove or in the oven. IDK about nutritional value research but a friend of mine once did an experiment. What happens if you leave a baked or boiled potato on your counter *indefinitely*? It will spoil, will it not? He left a potato cooked in a MW on the counter. The potato did not spoil but disintegrated and he watched it to turn into small black pieces that were not rotten, just weird. Can anyone here interpret this fact? Does it mean that MW changes food structure? Anyway, I never cook in MW and only use it for reheating and - rarely - for defrosting food. I am now curious and I am going to repeat his experiment but this time, using a regular boiled potato as a "control", i.e., I'll leave two potatoes, one boiled and one MW'd, unrefrigerated and see what happens. I just need to get some conventionally grown potatoes as I'd feel sorry to do it with my expensive organic ones, LOL.

A 120 V Speed oven isn't going to give you a whole lot of speed! If you have limitations that require you not install a 240 V, it might be the way to go if you really think you want both a speed oven and a microwave. A speed oven is a combination of a convection only oven (though some now also have limited broiler elements) and a microwave. What makes it "speed" is that it combines microwaves with the conventional (convection) cooking (i.e., hot air). Advantium also includes halogen heat in speed mode, which is an intense radiant heat for direct browning. There are steam microwaves, but most steam ovens are convection ovens (meaning hot air cooking only, but, again, some now have broilers as well), with steam environments. Some only have steam on and off, while others have several steam percentage settings. Some require you to fill a water tank and others are plumbed in like a sink with a water inlet and drain. Steam creates the kind of moist environment that you put pans of water or wine into your regular oven to create. It's very good for reheating leftovers, blanching or steaming vegetables, steaming tamales, dim sum, etc., steam poaching fish and chicken, steaming hard "boiled" eggs, etc. Because of limited cookspace in many European apartments, there are also lots of recipes for things like making rice in a steam oven, but that's for freeing burner space--it works fine but it's awkward. Anything you can make in a steam oven you can make just as well through conventional steaming or by putting the water in a regular oven. The steam oven just makes it easier. They're also generally smaller so people like to use them for small items. Because of the steam environment, you don't need as much surrounding space so there are a lot of large things you can make in a small steam oven. Unless you specifically want the speed settings of a speed oven, or you've decided that the model you're looking at is the best replacement for the conv./MW you currently use and you don't mind underutilizing it, there's no point in getting a speed oven. Steam ovens are nice to have, but not essential. If you're looking for something that will work as a small convection oven like your conv./MW (ignoring the MW part for the moment), then either a speed oven or a steam oven would do that. Since you'll already have a microwave, if you're looking for an additional function to go with the small oven, I'd choose steam.

Would like to add that it will also depends on the type of cooking that you do. Half the time or more, I cook Asian food, which traditionally is not calling for oven usage. There are many dishes that I now use the oven instead of stovetop though, all those steaming dishes for example. Another is the combi oven capacity, if it is a larger combi like Wolf or Miele, there will be plenty of room. For a smaller combi, it might be a bit tight having just one oven. I have a Miele which has broiler element, so it is as complete as a normal oven, except that capacity is a smaller (48l vs 76l for Miele 60cm), it can't do as high heat (225˚C vs 300˚C), and there is no self-cleaning.

Tomosakai, when you say "steam oven" are you referring to a combi oven that is also a fully functioning convection oven? Most people when saying it is the most used appliance because it can function as a regular oven with added steam being an option too. There are also dedicated steam ovens. Your first question is really about two things. 1. How can you provide extra moisture to a conventional oven? There are many ways. A pan of water or other methods can add a substantial amount of humidity depending on the size of the pan and if the water is heated sufficiently. To put things into perspective, amount of water generated while a cake is baking is the equivalent to a 30% setting on a Gaggenau combi oven according to their manual. How much more humity would a big pan provide? Will it take you to 60, 80 or even 100% of saturation? Bread bakers want a lot of steam with visible vapor(condensing water) or wet steam so they might spray water on the bottom of the oven or preheat a cast iron pan with lava rocks and pour hot water on it. This article discusses different methods from a baking viewpoint And why you need it. https://www.theperfectloaf.com/baking-with-steam-in-your-home-oven/ Some people might steam food on the rangetop burners or buy a dedicated steaming small appliance as above. A lid also keeps water from what is cooking in and steams whatever you are cooking in an oven. Jim Leahy's bread recipe uses a Dutch oven. 2. The second part of the question is how much extra humidity do you need to get the effect you want? If you read the manual to the Gaggenau, page 11-12, it gives you the idea of how much steam is provided in different settings. They don't really tell you the level of humidity on some of the other settings like defrost or reheat. If you look further they will tell you what levels of humidity are used in what situations. Anything you want to brown requires drying so that is the importance of the convection part. They do mention covering roast beef with a sauce while reheating to keep it from drying out so you wonder how much humidity does the cycle provide? https://media3.gaggenau.com/Documents/9000880517_J.pdf Whatever oven you consider read the manual to see what it actually does. These products vary considerably. Some are more forthcoming than others. You mention that the 36" oven will be your main oven but this oven will take much longer to preheat. For my own kitchen, I have a 36" electric oven in my range and a 30" convection wall oven. The wall oven is used much more because it preheats in 7 minutes and it is at eye level. I don't cook with a microwave but I am perfectly happy with reheating in it so it is in a cabinet by the refrigerator and away from my cooking area for anyone that needs to reheat. There are a few things I reheat in a pan or oven. I need the space in a regular oven and don't really steam anything. If I baked bread a lot, and had the space I might consider the combi oven for the convenience of the steam injectors. I do consider humidity In cooking. I use convection for drying to brown whatever I am cooking often for at least part of the cooking cycle. I add a water bath for cheesecakes. Electric ovens hold moisture from what is cooking so for cakes and muffins, this promotes starch gelatinization. Your gas oven is ventilated a lot more so moisture from food cooking is vented out pretty quickly. The important thing is to understand exactly what your appliances will do and how that fits with your cooking style.