I don't know about the Ronco so I can't comment on how it does.
We just got a dehydrator this year and love it. I've dried pounds of tomatoes that would gone to waste or I would have given away. (Only so many jars for canning and only so much space for storing them.) I've also dried more peppers, basil, sage, and stevia than I think we can use in a year.
The instructions say to slice tomatoes into 1/4 inch slices. 1/2" to 5/8" works much better IMO. They are easier to peel of the sheets to turn and hold together better.
Hope you still have tomatoes when it arrives. Happy Birthday!