actually poppets being faster makes a ton of sense. How far does a spool valve move to open the valve? At what speed? How how far and fast does a poppet move?
The answers are: along distance, slowly and a short distance, quickly.
The poppet takes less time to move from a closed to fully open position and less time from an open to a fully closed position. Thus, better valve resolution and more efficiency.
Then the problem isn't with the spool valve. The problem is with the engineer and where he is placing the open/close position in the rams stroke, and ram speed. There isn't any reason why the a spool can't have as good of a resolution as a poppet.
If we have two guns with the ram traveling at the same speed on both the forward and return stroke, and both are moving, lets say, 1/8 of an inch past where the seal is going to break, then both will open and close at the same time. Fully open for the poppet will be when the cup seal is at it's max travel from the valve guide, fully open for the spool is when the sealing surface has lost tangent with the o-ring, moved enough to clear the radius, and whatever material is forming the wall of the o-ring groove. You can do that in the same amount of space as a poppet, and since the gas doesn't have to hook three 90* turns you could shorten the dwell below the poppet valve.
sure, if you can move a spool valve as fast and hard a poppit, it will run like a poppit.
So if there's a current deficiency in spool designs that can be cured then you can build a better mouse trap. You can get an equal or lower reciprocating mass out of a spool so getting the speed isn't a problem. There's a path to building a better mousetrap here.
so if you make a spool shoot like a poppit, it will have the same type of performance as a poppit (ie kick), so why didn't you just shoot/design a poppit in the first place?
also, the reverse is true, if you slow down a poppit system you can make it operate as inefficiently as a spool, and be much much smoother the traditional poppits, but why would you? it makes no sense.
What if you could make a drop in assembly that gave you the efficency of a poppet without increasing kick? Lighten the bolt, massage how it seals, creative chamfering... I think this might be doable. There is no absolute that says a spool has to be either hard kicking or ineffecient.