And my old sewing machine service guy said he had a lady come in and her thread guide on the top of the machine had been cut off from years of using the invisible thread! I guess it was all she used. Weird it would do that.

I haven't used it on my regular sewing machine, but do use it in the longarm a lot. For what it's worth, I imagine it's about the same on both machines. It's true that it will eventually wear a hole/spot in the thread guides, but that does take a whole lot of usage. It requires a much lower top tension than normal thread. Pull on the thread once it's through the needle and if it curls alot, you're still too tight, so loosen it more.

Also, we typically find it best to use a non-slippery thread in the bobbin, such as a cotton or cotton wrapped poly (Polyonocore), so the stitches will tie off better. I prefer the poly invisible threads, since nylon ages, yellows, becomes brittle, and melts at a much lower temperature than the poly.

Just my experience. Hope this helps :)

Thank you so much everyone!