We had a combo unit, and one did experience an early demise. We were a little annoyed with the extra expense of buying another combo unit however what we discovered is that would have been a deal compared to what actually happened. Nothing on the market at that time would fit the cabinet we had, so we needed to replace that tall cabinet. Matching existing cabinetry is difficult, and we were getting no help there. In the end, the dead appliance morphed into a complete kitchen remodel. This time, we're doing our ovens as separate units, and we're making sure that the oven stack is made with separate components, so that they could be unassembled and remade in another size. What we had before was one tall cabinet, floor to ceiling, that was impossible to alter without destroying it because of the way it was constructed.

The received advice on the Advantium drawer was to make it as convenient as possible, though it probably is less important with the separate microwave. The glass tray for microwaving should not be stored high, and it does better flat than vertical, but since I'm pretty sure it's only for microwaving, you could put it in a less accessible place. Make sure you measure the trays. I think mine are 16" in diameter. They're definitely wider than my cookie sheets. Re flush integration, it's not that it's not functional when done that way. It's that it's really annoying. Because, definitionally, the door is stopped at 90°, or maybe as much as 100° if there's a big enough gap. If you're used to Euro cabinets that have that kind of limitation in the hinge, and are used to it, it might not bother you. I paid up big time to have step hinges so my cabinet doors would open fully. I don't often open my oven door (Gaggenau, side opening) more than about 135°, but when there's a big, heavy roaster or something, where one wants the strength of rigid bent elbows, it's a breeze with the door out of the way. Rolling racks were invented to rectify some of the looks issues that come with drop doors that cover the whole oven, or side doors that don't open the whole way, but there's nothing more convenient than just being able to reach into the oven and lift out your pot. Having one oven flush and the other proud, in a stack, will look weird. Different handles, colors of stainless and control panels, especially when there's at least an inch of trim between, looks fine. Different ovens of different sizes and different functions. But one innie and one outie will push it over the top, in my opinion. You might want to post another thread for info about the Bosch. Does the broiling element get used during speed cook? It may only have 9 pre-sets, but I can't imagine that it'll only do nine combinations. With the Advantium, if it's at all like mine, there are a handful of presets, but you can customize them, and you can also input your own. There's a steep learning curve, so modifying is worthwhile. Find something that sounds similar to what you want to do and change the time, or the amount of convection heat or whatever, and keep experimenting until you get just what you want.

@Amy Cantu We've been in our house for 6 mo now and I really like the GE Monogram oven. I haven't actually used the speed oven functionality of the speed oven. Just the microwave. And even then, we just use the add 30 sec option. I need to sit down with the manual and experiment with it. Unfortunately, using the speed oven is not as simple as just turning it on. It's pretty complex. I remember when I tried the speed oven at my friend's house it was really hard, and I thought I'd need to dedicate some serious experimentation to getting it to work for me, and doubted that I would ever bother using it as an oven except for Thanksgiving, which hasn't happened yet. My motivation to learn how to use it has been even less than I expected, so I'm sorry to say I can't report back. I also haven't tried using the oven probe functionality for the oven (haven't cooked a roast yet). Need to find the oven probe along with the speed oven manual! But I have done a ton of baking and roasting of vegetables and have been pleased. We were living in a rental house with a viking range and the GE monogram oven is 1000x better than whatever model of viking oven came with the range in the rental. Much more even. I've done two cakes side by side and they came out beautifully without the need to rotate. With a sheet of cookies I notice that sometimes a corner might brown a little quicker than another corner, but not so much that I really need to worry about rotating the pan halfway through. Broiler also works great--I've been making a lot of toast to go with steak tartare and an entire pan filled with toast toast 100% evenly under the broiler--hooray!

We have a stack of a Miele CSO and a Miele SpeedOven in a tall cabinet. The SpeedOven is at about eye level. I love the combination and would absolutely recommend it, if you have the space and the budget. But I am sure I could easily adjust to having the SpeedOven under the counter. We have a traditional gas range, and it comes with an "undercounter" oven, of course. We use this oven quite frequently, because of its very powerful infrared broiler. And that requires close inspection of the food while it is in the oven. Only takes a couple of seconds to go from barely brown to catching on fire. If I can handle staring deep into my oven, I am sure I can handle a microwave at the same level. That placement is maybe not ideal, but every kitchen is an exercise in compromises; and this seems to be one of the less annoying ones.