Why this is not optimal in Blender: If there is no way to get synced bakes via the plugin xnormal, you as Blender user have to stick to using option a) unfortunately. Option a) is thereby using way more polygons than optimal. This is because ingame the vertex count is doubled along UV seams anyway, using edge splits along the seams will give correct shading basically for free, meaning the vert count will not be trippled. In theory option b) is preferable as a) gets the poly count higher. What you can do about it: Either a) fix the smoothing of your lopoli before you bake via control edges or b) use edge splits. However, some game engines are not synced ( dont share any basis with a baker ) and thus will look strange on both MAX and Blender with default settings.

If that is the case you have done it right. Blenders viewport and baker share the same basis so normalmaps look how they should look. In that case you can flip your channels as much as you want, the in game shading will look wrong and blotchy. If a game engine or renderer wants a different basis then what the program used for baking can offer, it will always look odd like hitting smooth in Blender on a cube without control edges. They use a different tangent basis, Blender and xNormal share the same basis. There is more to it : A normal map from for example Blender is not the same as from 3DSMax.

Gamebryo engine normal maps