Understood - I actually CAN and DO hear the multiple synths playing, as all I have to do to accomplish that is to enable Input Echo On for the other layers, and they all sound together, even when either just playing or when recording.
Further, I can always arm each layer if I want to capture new data all in one shot. Editing would still be done on one layer and the changes copied over to the other layers, but overall I am not troubled at all with the process.
Perhaps a feature request to support more than one associated synth for a given midi clip or track would be a good thing to ask for. I don't know what would be involved in implementing it, but it certainly would raise the bar by having such layering available as a powerful option to the midi processing that is already very good.
Bob Bone