I have a 6600p and I use all kinds of thread in the machine it works fine. I am contemplating purchasing a Janome 11000. I wish I had purchased it as I will not need the 660P:. I got a price from where I purchased my 6600P for 3,500 for the 11000P On ebay they are 4-5,000. This is a new machine from my dealer in NH.