Sort of a mini rant and oversimplification, but IMMO, it is worth noting that much of the data on "ideal mash pH" comes from sources that were working on very different issues than what the average home brewer or IPA brewer is trying to solve for today. When Kunze and Narziss were working on this, the name of the game was making extremely clear, haze stable, and light colored pils of low gravity worts and optimizing mashes that had a very high pH due to using very pale and low-kilned, lager malts. Moreover they were largely concerned with the optimization of malt extraction-lauter efficiency, fermentability, viscosity, and achieving very low beer color. All while held to the restrictive standards of the RGB and without the use of most mash/kettle additives.
Per hopping, "smooth bitterness" is still the ideal within German brewing. When Kunze says to acidify the boil within the last 30 minutes of the boil, it is because they want to reduce isomerization - not to make the hop character shine - and ensure proper DMS removal... and ensure FAN and TSN levels provide high fermentability/pH drop using lager yeasts. That is not to say these are bad practices at all, but the reasons for doing so were not to make the best Pliny the Elder clone.
A very simple summary of German process could be to target mash pH of 5.5-5.6 (for attenution, protein break, wort viscosity, lauter effeciency and low color) with some form of lactic acid in the mash and then acidify in kettle to 5.0-5.2 for the aforementioned reasons. Final beer pH should be around 4.4-4.5.
In contrast, US/UK systems for pH control are different. Pale malts provide a higher pH drop in the mash due to kilning and the use of high Ca promotes a lower mash pH and ensures lauter pH stays constant. Compared to German process where you can see a swing in lauter pH, requiring reduction, 100-200 ppm mash Ca is normal and ensures the pH does not spike and the boil is at a relatively constant pH; 5.2-5.4. Bitterness is not a huge issue either, given the varieties used, and cultural tolerances for bitterness and hop character. Kettle pH reductions can be up to 0.3 pH, as Bamforth states, and is not uncommon. Final beer pH is lower, 4.0-4.4. Add in 5-10+% caramel/specialty malts and people often say, "what bitterness."