I have Janome machines and they do have the guide bar with their walking foot. (not the Horizon because that walking foot is built in) It stays in place rather well, but I'm a skeptic by nature, so I get out my duct tape. I tear a thin strip and wrap it around the bar on both sides of where it sits in the walking foot. Then it doesn't move at all.
Being the ever-loving fan of duct tape, If my machine didn't have a guide bar, I'd probably find a way to tape one on
