I have been targeting 5.4 ish simply because that is a number I see recommended often from professional brewers in regard to hoppy beers. Also see information from beers from time to time as well about higher finishing pH's in these beers.
One of the very first things I noticed when I started brewing NE IPA's and targeting 5.4 instead of 5.25-5.3 is that my kettle wort did not drop clear at the end of the boil. These beers are hazy at flame out for me. They are hazy after chilling, they are hazy in the hydrometer - that obviously has nothing to do with yeast or dry hopping. There are only three possible variables that are really at play at this point (before the beer ever even hits the fermenter):
1.) Flaked grains (which Brulosophy's recent experiment seems to discount)
2.) Lots of late hops at sub 170 temps
3.) Higher finishing pH
Other beers that I brew, even with similar grain bills, targeting 5.25-5.3 type pH..... The wort post boil, during chilling drops clear..... really clear. You can read a newspaper through the wort I put in the hydrometer in a "normal" beer. These beers do not do that - they stay very hazy in hydrometer and they do not drop clear - even if I let the sample sit there for a day or two. So, in my experience, it seems like something is already going on at this point in the process that is producing haziness as a byproduct of the process.
Right now, I have several experimental batches going. Maybe for my next batches I will brew two and acidify one to 5.2 and leave the other at my normal 5.4-5.45 range and see if that makes a difference.
I also wonder about the potential for different hops???? Do the hops we focus on (Citra, Simcoe, Columbus, Galaxy, Mosaic......) have oil compositions that play into the production of these polyphenols more than say your traditional IPA hops (Chinook, Cascade, Centennial, etc.)????
At the end of the day though, I think it is important to come back to the fact that the "goal" of these beers is NOT to make them hazy. The goal is that they taste great..... and, for whatever reason - it seems that haziness is an attribute that comes along with the flavors we are chasing. I am mainly just curious as to why that is exactly.