what do you mean by plugins? Let's make up an example of a simple game prop. Let's say it can have a 1024 normal map and it's intended use is in Unity3D. Does it make a difference then?
If you are going to export to Unity there are some undertakings on forum both here and on unity to make proper tangent calculator for xNormal for Unity. From my point of view it is not so obvious but there are some differences in how unity calculates its normals and tangents. Principe is known, just results are different…