I've never had a problem with any microwave not cooking throughout. Conventional ovens are uneven, they burn the outside and don't cook the inside sufficiently. Pans are just as bad, you get stuff heated more at the bottom than the top, and often burned onto the pan. The only advantage I can see for flatbeds is, as Panasonic advertise, you can stick any shape of dish in there. It doesn't need room to rotate.