Mark,
One Favorite catalog says "Not quite as deep as the regular skillet, the Miami Skillets weigh slightly less than the corresponding numbers in the regular lines. The three sizes listed (7-9) are excellent sellers and they are necessary in every complete assortment."
They are slightly smaller and shallower, too, then regular skillets. I don't see that they are of any less quality. I have a favorite (like in one I like) Miami skillet, No.7, nickel plated except on the inside with the early style reinforced top edge.
The Miami pans correspond with Griswold's Victor; Wagner's National, and Wapak's Oneta lines. All made them in only sizes 7-9 except that Griswold added a 5 and 6 in the early 1930's. Some of these pans go way back; Griswold's Victors appear with no pattern numbers making them c.1890 or so.
Quality of them all seems to be the same as the regular skillets. Price was less and I think they were somewhat of a cheaper line but of no less quality.
Steve