I propose a simple test. Brew three x 1 gallon Pilsner SMaSH Lagers at 10-12 Plato. They must be identical and identically processed sans for mash pH. Use distilled or good RO water, and add only CaCl2, and shoot for 50 ppm of Ca++. Process via the "no sparge" method so sparge can not influence the flavor outcome in any way. Mash one at pH 4.8 via phosphoric acid addition (since it is flavorless), mash another at pH 5.4 (also using phosphoric acid), and mash one at pH 6.0 via the addition of baking soda. Shoot for a relatively low 16 IBU's via the use of a single noble hop, added at 60 min. and 20 min. remaining in the boil, with 70% of IBU's from the 60 min. addition, and 30% from the 20 min. addition, so massive IBU's, and/or strong grapefruit flavors, dry hop flavors, etc... are not present to potentially mask and hide flavor differences within the malt itself. Drink each, and decide for yourself if mash pH control really matters.
Then (only if you did in fact notice any differences) repeat the experiment, only this time narrowing the three mash pH ranges to 5.2, 5.4, and 5.6. See if you can still notice the same differences for this "acceptable" range of mash pH's.
Flavor perception is unique to each individual. Only you can decide what your favorite mash pH target will be. Perhaps you will discover that you have no mash pH preference, and perhaps you will indeed have a preference. But asking others to decide this matter for you via a vote taken among those who have never tested a range of mash pH's to even know the real outcome themselves seems a bit strange.