I just tried this exciting new feature, very useful for me since I use Beyond Compare for advance file/directory comparison. I ended up a bit disappointed because:
1. You have to choose FileToCompareLeft OR DirToCompareLeft in the arguments: as a result, I need 2 menu items: one that says "bc2.exe FileToCompareLeft FileToCompareRight", and one that says "bc2.exe DirToCompareLeft DirToCompareRight". I have to remember clicking the right button depending on whether I selected directories or files. It would be easier for me to have only one menu entry "bc2.exe SelectedLeft SelectedRight".
2. It did make sense to have the difference between the two if "DirToCompareLeft" and "DirToCompareRight" where referring to the directory displayed in the panels, whatever the focused file: the second menu entry would therefore mean "compare the two displayed directories, not the files". Maybe you could add "DirDisplayedLeft" and "DirDisplayedRight"?
3. I have to select what I want to compare. This is a waste of time: I just compare two files or 2 directories, so what I'd like is to be able to compare the focused files or directories in each panel (e.g., FocusedItemLeft and FocusedItemRight). To be really convenient, this would require that the focused file or directory in the inactive panel be highlighted, but with a different highlight (in the same way the focused node background changes in the tree of the Configuration dialog box, depending on whether the tree itself is focused or not).
Finally, the possibility to pass the list of selected items is great, but... not available for the Editors configuration!

I'd like to be able to invoke for instance "TextPad.exe $(ListOfSelectedNames)" so that when I press F4, I open all selected files in TextPad...
I know, the users are always complaining...
So to finish on a better note: you do great jobs, guys. And I could not work without Salamander!