You are totally wrong about edge split thing. The vertices ALWAYS duplicated when any of the data is not same on it. So if hard edge or not same UV, or not same vertex color, your vertex is duplicated in the videocard.
But: when an engine loads a model, there is an optimization process, where the same datas are processed into a table (index buffer, vertex arrays - I dont remember the name). So if you have 1000 vertices on same position with different UV, the coordinate datas are stored only one times.
And there is no difference between apps. Blender edge split thing will make same results as Max smoothing groups or Maya etc.
For example read Unity docs, they write too: use edge split modifier in Blender.
I have worked on many games, using Blender as main modeler and level editor (so the objects are exporter directly from Blender into our game engine) and we have no problems with edge split thing. In one of my latest game we achieve very good performance on IOS/iPad1 game (Theendapp). And my older game Ignite now coming to iOS, and we can render many many vertices…
So Blender is perfect for game making. Now I am working on the #5 company where we use Blender as main tool in our game engine.
This topic is very sad, new example of the bad critisism of Blender… 
But ouf course, do not fear me. You are the future of Blender, not me. Your bad knowledge will rule everything…
Sorry for my bad english.