The solution is a DrawFilter applied to always align the text.  The filter would look something like this:

public class MiddleAlignDrawFilter : IUIElementDrawFilter
    {
        #region IUIElementDrawFilter Members

        bool IUIElementDrawFilter.DrawElement(DrawPhase drawPhase, ref UIElementDrawParams drawParams)
        {
            drawParams.AppearanceData.TextVAlign = VAlign.Middle;

            return false;
        }

        DrawPhase IUIElementDrawFilter.GetPhasesToFilter(ref UIElementDrawParams drawParams)
        {
            if (drawParams.Element is EditorWithTextDisplayTextUIElement)
                return DrawPhase.BeforeDrawForeground;

            return DrawPhase.None;
        }

        #endregion
    }

Then attach the filter to the Grid by setting the Grid.DrawFilter = new MiddleAlignDrawFilter();