I think you know the answer to your question.
Sir,
Don't get me wrong, but honestly, I don't. I'm just assuming that they should be the same, because the source is the same, but I could be wrong. I agree specific brand/model could make a difference, but I'm looking for a general answer/opinion. Enlightenment is bliss.
In addition, I also agree, if only I could afford such HDDVD/BluRay players, I would get both format. Unfortunately, upscaling is the most likely route for me.
Hopefully, they make those China generic HD-players which handles both format.