I think to have all three actions is redundant, and as the left/right actions are less powerful and less terse then the direct "move to..." actions, I think they should be removed.

Other information:
Also, somewhat related, when right clicking the task bar entry for a window which is not on the current desktop (when the task bar is set to show windows from other desktops) and I want to move the window to the current desktop, it would be much better to have - instead of the right/left actions - a "to current workspace" action.

Is someone actually using the "to right/left..."  actions? I don't see how they are usefull unless you only have two workspaces - this is the only case where haveing the "to left/right..." actions is better then the "move to..." action. 

As the title bar context menu is already sensitive to the number of workspaces as it has all workspace actions invisible when only one workspace is configured and has the "move to.." action invisible when only two workspaces are available, I think it would be for the best if the "to left/right" actions be removed when there are more then two workspaces.