Right now, the code for my symbol in the Map.xml config file looks like this:
<esri:GraphicsLayer.Renderer>
 <esri:UniqueValueRenderer Field="SUBTYPECD" Attribute="SUBTYPECD" DefaultLabel="Default Symbol">
  <esri:UniqueValueRenderer.DefaultSymbol>
   <esriFSSymbols:PictureMarkerSymbol>
    <esriMapping:SymbolExtensions.Json>{"type":"esriPMS","color":null,"width":21,"height":21,"angle":0,"xoffset":0,"yoffset":0}</esriMapping:SymbolExtensions.Json>
   </esriFSSymbols:PictureMarkerSymbol>
                </esri:UniqueValueRenderer.DefaultSymbol>
   <esri:UniqueValueRenderer.Infos>
   <esriMapping:UniqueValueInfoObj FieldType="Integer" Label="Overhead Fuse" SerializedValue="1">
                                <esri:UniqueValueInfo.Symbol>
                                                      <esriMapping:ImageFillSymbol Size="44" OriginX="0.5" OriginY="0.5" Source="/Images/MarkerSymbols/Electric/OverheadFuse.png"/>
                                                </esri:UniqueValueInfo.Symbol>
   </esriMapping:UniqueValueInfoObj>
  </esri:UniqueValueRenderer.Infos>
 </esri:UniqueValueRenderer>
</esri:GraphicsLayer.Renderer>
With this code, there is no symbol rotation (based on the value in the field SYMBOLROTATION) but I can manipulate the symbol size in the application builder, and the symbol image shows up in the legend. 
I can get the symbol to rotate if I use this code:
<esri:UniqueValueRenderer.Infos>
 <esriMapping:UniqueValueInfoObj FieldType="Integer" Label="Overhead Fuse" SerializedValue="1">
            <esri:UniqueValueInfo.Symbol>
                                     <esriMapping:ImageFillSymbol Size="44" OriginX="0.5" OriginY="0.5" Source="/Images/MarkerSymbols/Electric/OverheadFuse.png">
                                         <esriMapping:ImageFillSymbol.ControlTemplate>
                                              <ControlTemplate>
                                                  <Image RenderTransformOrigin="0.5,0.5">
                                                      <Image.RenderTransform>
                                                           <RotateTransform Angle="{Binding Path=Attributes.[SYMBOLROTATION]}"/>
                                                      </Image.RenderTransform>
                                                  </Image>
                                            </ControlTemplate>
                                         </esriMapping:ImageFillSymbol.ControlTemplate>
                                      </esriMapping:ImageFillSymbol>
                             </esri:UniqueValueInfo.Symbol>
 </esriMapping:UniqueValueInfoObj>
</esri:UniqueValueRenderer.Infos>
This rotates the symbol correctly, but I lose any control of the symbol in the application builder.  I don't mind too much having to change the symbol size using the xaml, but the symbol no longer shows up in the legend.  I understand why, but is there any way to tweak this so I get the best of both worlds?
Thanks!