There is no need to take offense. When you say that a unit's overall level of speed and performance is not an aspect of "functionality" but rather is an "output," I think you are engaging in a bit of semantics. The point is that responsiveness impacts the user experience, which is why there is so much interest in the HR24. But, let me once again issue my earlier caveat: I have NEVER used an HR23. I don't think I've even seen one. So, I'm only telling you that others are concerned about it's responsiveness. I can't say whether or not that is a valid concern.