If you put "Millers Falls Home Page" into google, you get to a web site which contains this:
When the Millers Falls Company introduced its new line of hand planes in 1929, it needed a way to differentiate its products from others already on the market. The identity problem was compounded by the fact that all of the new models were knock-offs of existing Stanley production. The company chose to build product identity by concentrating its publicity on the new line’s flagship tools—the bench planes.
The planes were developed with an eye to creating an instantly identifiable appearance that would set them apart from the competition. The frogs were painted with a bright red enamel that contrasted sharply with the planes’ black enameled beds. (Frog incorrectly colored black in this illustration.) The company adopted the use of a highly polished nickel plating for the lever caps of its premium bench planes and displayed the company name on them surrounded by bright red paint.
The other way chosen to distinguish the bench planes was the promotion of the design of their jointed lever caps. The standard lever cap used by competitors applied pressure to the chip breaker/cutter assembly at two points—one at the point of contact with the cap’s cam lever, the other along the lower edge where it made contact with the hump of the chip breaker. The hinged cap was designed to apply force to the chip breaker/cutter assembly at a third point, just above the chip breaker hump. Three points, rather than two—the company advertised the arrangement as a method for preventing chatter. The jointed lever cap was was developed by Charles H. Fox, a Millers Falls employee who assigned the patent to the company. A copy of the patent document is located at the Plane Patents page maintained by Tom Price.
The Millers Falls Company would eventually offer several less expensive bench planes that featured traditional lever caps. The least expensive planes were initially marketed as part of the Mohawk-Shelburne line of economy tools. Later versions bore the Millers Falls trademark. The company also manufactured several intermediately priced planes equipped with traditional lever caps. The most unusual of these featured beds with teflon-coated sides and soles.
From that, it's hard to tell if the need for a gimmick led to the design or the cleverness of the design led to its adoption.
As it happens I've got a Millers Falls 14C (a No. 5 with a corrugated sole) which I've fitted with a Veritas retro-fit iron and have set up as a sort of scrub plane. The lever cap holds the iron well but without a normal cap with which to compare it, I can't say if it's better or not. I imagine that somebody who has made precisely that comparison will come along and cast light on to the matter.
