We haven't done this either, but like Larry, I have seen it in other units.
Depending on how tall you folks are, one thing I would caution on--- If you decide to install it up top side over the range where the present microwave is, think about taking that HOT stuff out of there. Especially if it is going to be over your head or at face level. That would be awful to slip with hot stuff right at face level. We have thought of that happening even with the micro. If I was going to do this, I think it would where the oven is and the upper area would become storage cabinet space.
2008 Cruiser CF26RK
2013 Ford Eco-Boost
Heavy duty payload - Max tow