Gill-T
You are correct that certain species do tend to exhibit more ram speed (closing speed relative to prey item), especially when feeding aggressively. When fish are not feeding aggressively, all species tend to have little to no ram speed. This is based on watching hundreds of hours of underwater footage we collected while doing product testing.
We caught over 1,300 fish while doing data collection, the majority of which were silver fish on spoons. Half the lines had Strike Assists, the other half did not. The Strike Assist rods averaged 36% more fish and cut the landing loss in half (33% to 14%).
Captain Bob Hinds (Central Coast Angling) used Strike Assists on all his spoon rods last year. He caught over 300 fish with Strike Assists, mostly kings, and had a 95% landing ration. He said normally it is around 70% without Strike Assists.