The ‘Vibration’ rods simply became too heavy and too expensive to make as rod technology advanced and rods became lighter and cheaper.
From an angling point of view, the underlying principle of Grant’s fishing techniques was the desire to present the fly through a pool with the minimum of disturbance to a holding fish. In other words, his intention was to try and keep the distance from his position to the salmon as great as was possible, hence his desire to cast such distances. To do this, he used almost exclusively his Grant’s switch cast. A detailed description of this cast can be found in Jock Scott’s excellent book ‘Fine and Far Off’ where actual cinematic footage of the great man demonstrating the cast was used to show its correct execution. It would be fair to say that the Grant switch cast was the forefather of what modern-day anglers would recognise as a Single Spey cast, but unlike our modern version, Grant shot no slack line on the forward delivery. He kept a uniform length of line through the pool and did not believe in induced taking techniques like hand-lining. He preferred to utilize the stream to present the fly by using mending techniques
Another foundation of his fishing technique was the desire to at all times control the swim speed of the fly through the stream by keeping the fly line dead straight from his reel to the fly. His intention was to have the fly under control and fishing as soon as it pitched on the water. As a result, many fish fell to his fly early on as it swept through the pool.
It’s also worth noting that Grant rarely, if ever, struck into a salmon, rather allowing the fish to take up the tension in the line to hook itself. He strongly believed that the fly, when fished on a long line, presented slower to the fish than a shorter line, resulting in a firmer hook-hold. In the vast majority of cases, he basically allowed the salmon to hook themselves. He is reported to have said “The surest-hooked fish, all being equal, is with a long line and none of this nonsense about “Hitting a fish on the rise!”
He was also very critical about the effectiveness of greased line fishing, believing that a floating line put the fish down. He argued it was alright if only the fly came within the fish’s optical window, but in his own words “ no fish would like to see a big, black snake floating over its head as the line would look dark to a fish looking up at it against the light”