I know of no other language that comes equipped with such a complete and consciously arranged phonological map. As you well know, no language has changed more over the centuries than Japanese--first with the introduction of kango from the continent and now with the introduction of a plethora of katakana terminology. Yet phonologically, the language remains virtually unchanged--no morphing of vowels, no drifting of consonants. Really quite extraordinary.
I am always surprised when I see such assertions, for there is another language that comes to mind immediately:
For those who would like some assistance unpacking the chart, the page in which it is embedded can be found here.
But perhaps I am missing what you would regard as a critical distinction between the two.