I am pretty sure there is no way to do this currently in Blender, but I would like to be able to add an edge loop and have it respect the curvature of the two edges, but be restricted to the profile of the verts on the endpoints. This might not make sense, so I posted two images that show the behavior of Loop Cut and Slide with %100 smoothness. It’s almost right, but it overshoots the endpoints and has to be flattened. It would essentially be the same thing as what happens when you initially bevel an edge and add roundness- it maintains the profile of the end faces. I can do it with Mesh Machine’s Fuse, but I feel like this should be native to Blender. Max and Modo both have this feature, and it’s really handy.