This is not a direct answer to your question but something you may want to think about. Do you use your regular microwave alot during meal preperation? I do, to heat leftovers, cook, etc. I hate washing pots and I don't like cooked food standing around while something else is in the process of being cooked. I have an excellent convection microwave as my "second oven" which I can use to do almost everything I can do in my large oven. However, I came to realize that if I use my conv/micro wave as my primary oven to cook my main dish, then I can't use it as my microwave to warm the veggies, etc. at the same time. I often laugh when I think, "wow, this is great, I need another microwave". If you cook like me, you may want to consider this. Just a thought.

I was wondering about the differences bewteen the Miele Speed Oven vs. Wolf Convection Microwave?

We rarely have a need for a microwave, but after doing without for three years I knew I wanted one. We opted for the Bosch speed oven, and use it much more than I thought I would. Use is about 30% speed cooking, 20% microwave, and 50% of the time we use it as a small convection oven. However, the oven that has fully won me over is the steam oven. It is wonderful, and after some glitches with the control board it is working flawlessly (Bosch has been top notch for repair and service). It does everything that a regular microwave does except pop corn. Food reheated in a steam oven doesn't even compare to food reheated in a microwave. I've used all three (speed, steam, full size convection) at the same time on quite a few occasions and love having them all. However, if I had to pick just one of the smaller ones to go with my full size it would be the steam. I'd put a tiny microwave in the pantry for that rare need. Good luck with your new ovens!

So, make a niche(s) with the proper electric service and size to have a built-in put in if you really need it to sell (but I bet you won't)--if you're planning to sell within three years, get the built-ins already, but otherwise, they're going to be just so many used appliances. If yours are truly ratty, you can buy new versions of each. If you WANT a speed oven, and intend to use it as such, that's another story. Go for it! Read through the manuals, etc. But I think you'll find that it's not at all the same thing as your Breville toaster oven. You can use the convection oven settings on a speed oven to perform some of the same functions, but it's a real oven, with limitations, not a toaster that tap dances. I sometimes use my speed oven the way others use a toaster oven--mainly for heating up frozen appetizers or reheating casseroles when other ovens are full, but my old (dead) toaster oven was beloved for making great toast, which a speed oven isn't, and not for other uses. I do zap sandwiches on MW mode, and once in awhile lightly defrost or melt, but if I used a microwave more, I wouldn't have such an expensive machine doing it. I agree with putting enough thought into a remodel that it won't limit resale, because you never know what the future will bring--thus make sure there's place for built-ins to be built into--but unless it's a flip, it should be designed for your own use and enjoyment, and you used the key words "heavily use" and "love".