The OpenTK.Input.Mouse.Move event has been commented out since r1303 (2008-05-04), with the log message "Temporarily remove MouseDevice.Move event, due to issues with deltas when the mouse stops moving."
Are these delta-related issues still existent? If so, are there steps to reproduce? I haven't personally noticed anything that looked wonky after uncommenting it in my local copy while running on Win32 or OpenSUSE.
[Moderator edit: trimmed title.]