Currently, during a 3-way merge, the shown differences are always between Remote/Base and Local/Base.

It would be great to have the possibility of also showing the differences between Remote/Local.

Why? Sometimes the Remote and Local files are exactly the same and since the differences are marked on them when compared to Base they seem to be very different to each other. We have then to open or copy/paste both Remote and Local files on a file editor and then compare them, to see that they are exactly the same.

This is quite common, because when we use squash in Git we end up with branches very similar but with quite old base files...