I have only had my 15000 for about 6 weeks and I free motion quilted my first quilt on it last week. I used the machine settings and the open toe free motion foot. I was very pleasantly surprised with the stitching and the foot. It was very smooth and I didn't have one thread break. I am probably an advanced beginner with free motion and was very pleased with my results. I still do not have smooth curves and nice lines, but I am trying.
I just picked up the convertible free motion foot and the ruler toe because I had already gotten the ruler foot before I traded my 8900 in and never got to try it. I am anxious to see which foot I like better and will let you know.
Gail in FL