Mark: I certainly HOPE my experience with the U25C wasn't typical, but since neither of my NP would run right, I'm going to rewire the CB&Q and BN before trying them. I posted my experiences as much to show how easy it is to fix the problems, if one does have them, as to complain about the quality. Of course, if Arnold chooses to redo the pickup system it wouldn't hurt.
As for the size of an SW1, I doubt that it's any smaller than a MT Z scale F unit, and those run quite nicely. I have two Nn3 boxcabs powered by them.