It would be really nice if there was a “Remove input edges” option in the Command line while running the “InsertEdge” command of SubD. I know that a subsequent selection of the input sub-object (the loop or ring edges) could be deleted with the Delete key, but it takes extra mouse clicks and holding of Ctrl+Shift simultaneously. 3d mesh modelers based on Catmull-Clark subdivision usually have their chamfer tool doing that automatically or by a tick to turn on or off that option while the command is active. Also, having to manually select and delete the input sub-object (the edges) after executing the “Remove input edges” command makes it impossible to have a nice preview of what exactly the user would expect while adding extra loops or rings of edges, with the input ones being removed automatically.
this sounds like a good idea to me-
I’d use Slide if it were just inserting one edge and wanting the input edge gone afterwards… or Bevel with 1 segment if inserting two edges at the same time and wanting the input edge gone. I’m fine with another option on InsertEdge too of course if possible but those two methods may help as well.
Sometimes, “InsetEdge” and “Bevel” show quite strange behaviour, this is why if one of these fails I try the other one (or vice versa). I had several instances at which “InsertEdge” was the better option for adding new edges at either side along the selected loop of edges, where “Bevel” failed. Then I had to delete the input edges in the middle to leave the new ones only. In some other instances, however, “Bevel” worked properly where “IsertEdge” failed.
For example, the following video shows how “Bevel” behaves while trying to make a larger bevel along the selected edges. It simply stops upon reaching some amount of distance. Looks like there is an invisible limitation that prevents it to make a larger beveled edge. On the same geometry, “InsertEdge” refused to add edges at the opposite side of the input edge loop, even though the geometry itself is basic (3d mesh programs such like 3DS Max don’t have such an invisible limitation).
Thanks, I filed these for the developers…
Your initial request for InsertEdge to have a remove input edges option:
https://mcneel.myjetbrains.com/youtrack/issue/RH-64679
For the Bevel limitation:
https://mcneel.myjetbrains.com/youtrack/issue/RH-64677
For the InsertEdge self intersection:
https://mcneel.myjetbrains.com/youtrack/issue/RH-64678
Thank you for considering these for a future improvement! SubD is new to Rhino and works nicely even at its current state, however, it has the opportunity to be even greater with some minor tweaks here and there. 
I’m unable to flip the direction of for the “Offset mode=Absolute” while running the ! _InsertEdge command. No matter where I click along one of the target edge, Rhino will always prioritize only one side of the edge and will not let me flip the direction for adding an offset loop/ring of edges from existing edges. Adding a new Command line option called “Flip” (or “FlipDirection”) would fix that.
I’m aware that the “Loop” mode could be used as a workaround, but lacking an option to flip the direction is a weakness of the “Ring” mode.
Check here for example. I try to add an offset from the right edges marked with #1, but Rhino prioritizes the left edges marked with #2. This is kind of annoying.
can you send us this part file so we can try to reproduce?
It’s not the same model, but here is a similar topology I created to show you the issue (bug?) with inability to flip the direction for the “Absolute” option.
Insert edge bug.3dm (147.9 KB)