In an electric slider chest, the key channel acts as the "expansion chamber". However, when the pallet closes, it still slams shut, and the pipes are stopped in "mid sentence"....so to say. Applying the slower opening and closing of the pneumatically operated pallet, these "abrupt" speech problems disappear. The leather argument will always be there....that's one that has carried the electric valve action into modern times, and made it many friends.
The great claim of electric actions....No extra leather to make the action work...(and rebuild)...just the leather faced valve, itself. However, in an electro-pneumatic slider chest, there is actually about the same leather expense to redo it, as there is to rebuild an electric valve action. You only have the primaries (sometimes the primaries are electric) and the 61 pneumatics under the pallets to recover. That's a heck of a lot less labor, than taking down every valve in the chest.
Yes, provided the valve faces in an electric valve system don't get wet, the valves will last a long, long time. I've never redone a set of electric valves that were rotted out. The roof on the church doesn't last as long! Water damage from a roof leak has always been the culprit that took the valves out of commission as far as my experience has been. So there you go, electric valve fans....another good selling point!
There are a lot of advantages to the electric valve, if one only looks at the practicality of it. (In a review I've started for a friend of mine, looking toward a digital organ), there has appeared in the sales literature, an amazing array of digital "sounds and noises" in the digital samples that are programmed into the pipe sounds....so that the digital "pipes" will make the same identical starting and stopping sounds of a real organ pipe. That's one channel you might investigate, to learn more about what these sounds do, in making an organ pipe more "musical".
But...dear fellow forum members, don't dwell on this too much. It can drive you crazy! Take that from this old pipe organ "nut" who goes around his house, cutting nicks in the whistles of his cookoo clocks, just to get rid of the chiffs.
....."next" is a four letter word. Jay999