I have used it. I only use it in the top.
I have used Superior Monopoly
http://www.superiorthreads.com/shop/...brand=MonoPoly
And I have used Filtec Essence
http://www.bobbincentral.com/embroid...d/essence.html
Both products I used clear, not smoke and only from the big cones. Both require a thread "sock" on the cone to keep it from unraveling too fast. Both products came with the thread sock.
I had to loosen the top tension quite a bit.
On both products I used a prefilled magnaglide in the bobbin. Both products I used to do ditch work. I have ditched both piecing and applique with it. I have not used it for fill work.