I saw some at a quilt show, spoke to the salesgirl and when I told her I use Machingers, she pooh-poohed them and told me that was why I had trouble with FMQ (mind you, I have a table with a rubber lip, no easy glider mat of any kind, and am a noob, so are you SURE the Machingers are the problem?) Needless to say, she was selling her halos for domestic machines and telling me how great they were. I passed, because I didn't have any $ with me, and there was no set up for me to test-drive the halo. But I have wondered about them and whether or not I passed on a tool that would really help me out. I only quilt on a DSM, so I am very curious to see what responses you get on this thread. Good luck and DON'T GIVE UP!
PS sorry, my response was not particularly helpful, was it?