I feel your extensive review captures very well the elements to consider. There was a thin line between usefulness as a chronograph and the minimalist aesthetic of the Altiplano line, which Piaget navigated fairly well. I guess that for the numbers sold, a completely new, proprietary movement not based on the existing automatic one would be difficult to make a business case for, so the compromise solution is next best.
Looking forward to seeing it in the flesh - thanks for whetting my appetite