CR doesn't test speed ovens but it does test combo wall ovens. The upper microwave oven of the Bosch 800 Series HBL8753UC combo oven performed well and you can buy it separately as the Bosch 800 Series HMC80252UC or Bosch Benchmark Series HMCP0252UC speed oven. So if you didn't need a second full-power, full-size oven you could install one of those alone.

I have a Miele Speed oven which was installed 2010. MW functions like a normal MW. It has 1000W (??) of power (not sure) It does not have a turntable. You have to turn the food a bit now and then. I am not a heavy MW user. My other oven is a gas range/oven. Because the speed oven heats up faster and is very even, I rarely use my big oven. I can't remember the last time I used the large oven.

If I am baking cookies, I preheat the speed oven. Oops, I forgot to melt the butter. Switch the speed oven to MW, melt the butter, turn the oven back to preheat. I can bake 2 trays of cookies evenly in the speed oven.

I have a GE convection MW elsewhere and that is not nearly as functional as the speed oven.

You do not need another MW,