Through much trial and error, I found that I could obtain my desired tonal tweaking with electrostats by adjusting both toe-in and tilt. Abstract7's suggestion also affords the ability to play with different sound absorption material on the rear panel which can be very beneficial as well as fun. Other "room tune" devices can help as well. With electrostats, it truly is a labor of love. Good luck.
Electrostatic positioning 1A
Here's a twist on this well-flogged subject: Bass vs. depth vs. midrange vs...How to restore the midrange balance when positioning speakers far off the front wall? The situation: when placed more than a few feet off the front wall the bass and depth are great (good news), but the vocal image becomes less palpable (ugh). Placement restrictions create only these two options. How do I restore the vocal presence that's there when the speakers are closer to the wall? Can we have it all?!