Standard shader, instancing and MaterialPropertyBlock

While doing some performance testing drawing cubes, I noticed that when using the standard shader the batching doesn't work when I use MaterialPropertyBlocks in the code to change colors. I then tested a new surface shader I created with the Create Standard Surface Shader menu option which had the same problem. However an instanced shader I created with the Create Standard Surface Shader (Instanced) menu option in 5.4 or 5.5 worked properly, but that option is no longer available. Did some more testing and noticed the cause in the shader code.

Fast with MPB colors:

Code (CSharp):

1. UNITY_DEFINE_INSTANCED_PROP(fixed4, _Color)

Slow with MPB colors:

Code (CSharp):

1. fixed4, _Color;

Does this mean that if you want to use MPB:s to set colors to instanced objects, you should use your own shader, or is this something that can be fixed with the standard shader?