Derek Cohen (in Perth, Australia)
My logic says that the Stanley and aftermarket chip breakers (several but they share certain qualities) came about for similar reasons but managed differently.

When Bailey posted his new invention, he considered that the primary advantage was to reinforce/support a thin blade. Over time this became the identity of the "cap iron".

Over the years there have been a number of aftermarket versions. Record (and then Clifton) brought out their Stay-Set design. Frankly I am not sure of its purpose, other than to offer a way of sharpening a blade more easily (just remove the front section).

There is not a lot of difference between many of the vintage infill-woodie chip breakers and the more modern offering of LN and Hock - all are essentially flat pieces of steel with a bevel at the end. The LV, by contrast, is similar to the Stanley, but thicker, with the facility to create pressure at the bevel end. I would lump it in with the LN and Hock, however, as the steel is 1/8" thick.

Several years ago the first review I attempted was the LN chip breaker. Not knowing any different, it was set further back on the blade than effective. Nevertheless it was apparent that it was able to effect an improvement over the original Stanley. I can only assume that this was the extra mass/stability at work. There is definitely something to be gained from extra mass in the blade, and the thick chip breakers will offer something in this regard.

The other advantage of the aftermarket chip breakers is that one can hone them as if they were a blade. The angles are more predictable. More of the Stanleys I have seen are rounded at the leading edge, and their springiness makes if difficult to decide what is their effective angle.

Lastly, the relationship between bed angle and chip breaker angle is not clear. The video used a 40 degree bed and recommended 80 degrees. By extension, a 45 degree bed should use a 75 degree leading edge, and a 55 degree bed should use a 65 degree leading edge. Off the top of my head, the leading edge of a LN chip breaker is 50 degrees.

If the aim is to re-direct shavings - the vertical seems to be the goal - then the angle that the leading edge meets the shaving appears very important. Research for someone!

Regards from Perth

Derek