Interesting
I did my own version of the signal path to start API v5 (beta 00.00) it was indeed very helpfull!
There is one input missing in my opinion:
THE ITEM: this is the main sound source that you will use in reaper. The monitoring fonction gives you the choice to hear the direct input, or the item, or both.
Also, don't forget that you can record the input OR the output of the channel strip, you should have a way to move the record button on the chain. Same goes for send pre or post fader, but there is no way to use this parameter to change the layout as far as I know.
That's the problem: the signal path in reaper is way too flexible to be drwan!