Hi marc, so for the next MoI v4 beta there will be an additional option under Options > Import/Export > SubD import options > "Open boundaries: Keep corners" or "Open boundaries: Rounded".

The default will be "Keep corners" since that seems to be more common than I had thought and it also actually makes a simpler result too. But you'll be able to set it to Open boundaries: Rounded which will then give the current version behavior.

- Michael