Both of the changes discussed above will be available in the April 21, 2020 Rhino WIP.
For MergeFaces I added a persistent
Results=Selected/NotSelected option. I don’t like the option name, but I’m guessing an option name like
SelectResults might be confusing? ( https://mcneel.myjetbrains.com/youtrack/issue/RH-57952 )
For Delete I simply removed the selection of the boundary around the deleted faces. We don’t select boundaries when mesh or polysurface faces are deleted. I thought selecting the SubD boundary might be useful because I was guessing that a command to fill or extrude the boundary would be the next thing to happen, but it is pretty easy to pick the boundary in that situation. ( https://mcneel.myjetbrains.com/youtrack/issue/RH-57976 )
In any case, please give it a try when the WIP ships tomorrow and let me know if the changes address the workflow problems you all pointed out. Thank you for the input and please continue to help us make SubD tools more useful and less annoying.