It was poly Gutermann. I also sew garments/curtains and it works for that. Most quilt stores here either have their own preferred brand of thread, sometimes depending on whose machines they carry, or just carry fabric. Try finding anything different in Joannes, Hancock or Hobby Lobby. I prefer Metrosene for garments, but you can't find a large spool here. The shop where I bought the thread is also a Bernina dealer and the thread is in with Bernina.
I'm not dissing any dealer - they have to sell, support and believe in what they sell. But this post didn't solicit any dealer-type praise for the thread. You mostly found it worked on your own and said so.
I was using the long skinny plate for the Mini iron as I'm tired of accidently burning fingers or not being able to see what I'm doing. I'm not nearsighted, just like having things right under my nose. The skinny plate just covers 1/2" or an open 1/4" seam.