I think your overlooking the pressure differential created by the pistion travel. I think this force is far greater than any exerted on the reed valve. The fact that the rubber valve has no spring action proves this. granted it will have more mass therfore there will be more inertia energy to overcome to get it to stop change direction and go back to the seat. so what is this force if its not spring action in the reed itself. it has to be pressure differential.
The reed needs to reverse directions and get back down and close off the intake port so the transfer phase of the cycle can start. If it lags a bit there won't be as long a duration of transfer and performance will suffer.
The reeed valve has no effect on the transfer phase of the the cycle. this cycle starts as soon as the piston opens the transfer port and ends when the tranfer ports are closed by the piston. the only way to change the timming of this cycle is to change the intake port timming. I think what you are talking about is the lower end compresion cycle. true if there is a lag it in effect lowers the duration of the lower end compression cycle. this in turn creats a lower pressure differential and there will be less pressure energy to force or transfer the air and gas mix through the ports and into the cylinder during the transfer cycle when the transfer ports are open.