I have a Janome 9700 and Threadart poly is part of my thread stash. Only had a problem with one spool and I'm sure it was due to the dye as the color was so dark. Otherwise no problems.
Part of my thread stash is from Threadart. I did have a problem with one spool but it was because of the amount of dye in the thread, no problem with any of the other 30 or so spools.
yes I have used this in the past on both my Janome 10000 and on my Janome 350e. I have had no problems with it and in fact have an order on the way being shipped to me now.