I feel your pain because I am going through the same and I want my original Amana microwave back.
i had a larger Panasonic for about 18 months and then it started overheating on defrost until finally it burnt a dish of green beans that were in it on the keep warm feature...they were in for 10 minutes until we wondered what that smoky smell was. Not on warranty any more.
i did a lot of research on what would be a good replacement...I do not have my notes anymore and got really confused with all the different model numbers from Panasonic and all the conflicting reviews. I also want the inverter. I ended up getting the Panasonic model NN ST6815..it had a lot of favourable reviews and was available locally. That was about 3 weeks ago. All was well until a couple of days ago...the defrost heats too much as in bringing the liquid in frozen baked beans to the boil . I weighed it and it was not in too long. I had noticed other items seemed too hot after a spin at defrost. So, it is going back soon for either another or a refund. Not sure what to do. I too would like other comments.
I am rethinking the whole microwave idea. I like the keep warm feature, I like the defrost feature and other than that we use it to reheat stuff. So maybe I just get a cheap one and forget the inverter.