I LOVE my Juki. I use it for piecing and have it on a GMQ frame. I can't say enough good things about it. One of the best things for me is that it is completely mechanical, and can be oiled. There is nearly nothing to break on this machine. No computer, no plastic parts. If you keep her oiled, she will run forever.
I do take her on and off the frame, and I wish I had two of her. Actually, now I want a long arm, and I am seriously considering stretching another Juki. She rules as far as I am concerned.
The stitch regulator is touchy at first. But Grace is a truly amazing company to work with, and so far have solved all of my issues with a 5 minute or less phone call.
I bought my whole rig at Sew-Vac and they were also wonderful to work with. The only thing I would add to your list is leaders- I bought leaders from Kathy Quilts, and they are holding up fine.
Test drive, but if you want a quilting workhorse, the Juki is your girl.