By the way, I did test the "mark" function using the remote control app - it works fine.
When you press the "Mark" button, which is commendably large, you get a message back giving the mark number (useful if you want to make a note of what happened at that particular mark).
On playback (using the remote), if the "mark skip" function has been enabled on the recorder, then holding down the "mark" virtual button and at the same time pressing the skip forward or back button, playback skips to the next or previous mark. If you are playing back via the streaming function, you may find some buffering happens because you are streaming the relatively large amounts of data in a BWF file, not an smaller mp3 (which doesn't support marks).
Chief missing function now is the ability to select a file in the "browse" screen of the app, and play it rather than copy it (copy is the only option offered once you have selected a file remotely). At present, the only way to play (or stream) a particular file from the app is to use the forward or back skip buttons until you find yourself at the right file. On the device itself you can of course browse to a file and play it or delete it etc.