The problem with the Sure Fire was it used to bend over time and from what I remember of ours would not work properly!
They were also developed with the leash attached for the old system on the outside line.
Yes the Surefire had a lot of problems - some of them stemming from the rotating leash system. I have a Surefire bar but don't use it.
I think its great that a company has decided to build one of these and I hope it becomes an industry standard.
I did a bit of thinking over the years of how one should work.
In my concept, the bar would be the same as the Mystic one except the hooked end on the bar casting would be missing and there would be a hinge where the straight bit started to curve into the hook. The removable hook would only include the straight top piece and have a pin through it for the hinge at the end of the straight top piece (where it started to curve into the hook).
For a release I thought of a blade-type lever on top of the casting hinged at the spreader bar end (and sping-loaded to keep it central), and you pull the outer end (nearest the hinge) of the blade to either side to release the inner end of the hook extension. A small curved ridge on the casting just outside the end of the release lever to stop a line getting under the lever.