There doesn't seem to be much discussion of intraday MP, or at least I haven't found it, so I appreciate your effort.
I don't use MP per se, at least in terms of all the calculation, but I do look at the day in terms of a volume range and a price range, which I hope is not too far off the MP intent.
Therefore, your take on this seems perfectly reasonable to me, though I arrive at more or less the same conclusion from a different route. For instance, the price and volume ranges established Wednesday put a midpoint around 625 (this may or may not coincide with the
POC). Therefore, I'd be looking to enter somewhere near 550 and exit somewhere near 700 (or vice versa), depending on what opportunities present themselves before the open and during the day. But I'd also watch the 625 area since price may just decide to reverse and end up back where it started.
And, yes, it is interesting to see how price travels among the midpoint and the extremes. Auction market theory definitely brings something to the table.