I got one with my HandiQuilter LA, and loved it. Then when I bought my industrial Juki, I really hated winding bobbins on it, so I bought one off Amazon and it was too fast and I had problems with it so it got donated. DH even tried to make some modifications to it and in the end told me to go ahead and spend the money and by other HQ model.
My Juki bobbins have the same hole diameter as the class L, so they fit and you just move sensor so it shuts off at the right spot. The bobbins for my Babylock don't fit, but I use mostly prewound for that (embroidery) so it's not a big issue. I think if I put some black tape on the spindle I could get it to work, and I might do that so I can wide up a bunch of black bottom thread bobbins.