Maybe my terminology is bad - by isoparms I mean just edges,anyway,current selection system is fine but I think good solution would be to be able to have also seperate hotkeys for selecting :

- solid object
- edges
- construct edges(the edges which very used to construct object)
- faces

Like in poly application, when I press proper hotkey will be able to select faces only or only edges.
It could be useful when you are working with only one object,so you don't have select solid first all the time just to select edge or maybe it's complicated object and you want to filter some selection possibilities.

I think it could be useful to have an option, when you disable history, to remove construct edges because for example you don't need them anymore and you don't want to clutter workspace with them.