I think we're going to go with the Miele based on the price, Master Chef programs, and larger interior dimensions. Here were the upsides of the Gaggenau as we perceived them:
The Gaggenau ovens have more power heating elements and a smaller interior volume, which presumably means they preheat faster and return to temperature more quickly if the door is opened and closed. On the down side of course, they have a smaller interior volume.
The Gaggenau ovens have a higher maximum temperature in many modes compared to the Miele. The BO 480 can go to 550F/300C [1] in convection mode, while the Miele H 6880 BP will only reach 475F. For the combi-steam ovens, the Gaggenau can reach 450 while the Miele will only go to 435.
I like the Gaggenau controls a lot more: turn one knob to pick the mode and turn the other knob to set the temperature. The Miele, on the flip side, is more programmable and the M-touch series has a ridiculous number of built-in programs; to an extent richer features require more complicated controls, but I think Miele could do more to make basic use easier.
Gaggenau has been making plumbed steam ovens for a much longer time than Miele, so there may be less risk of being a guinea pig.
Both brands suffer from purporting to achieve a humidity percentage rather than letting the user set the wet bulb temperature directly. I recommend reading the section on combi ovens in Modernist Cuisine, volume 2 (get it from your local library), which lauds combi ovens but goes over the science of why fine-grained humidity control is largely bupkis.
I wish I had the time to reproduce the experiments they performed on the Rational combi ovens on both the Miele and Gaggenau to see how well they perform in practice.
[1]: 300C is 572F. I've contacted Gaggenau to figure out whether 550F or 572F is the real maximum temperature, but I'm still waiting to here back.
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love all the glass,question, why separate windows?
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