Obviously, there is a point where creativity is required to tune the math to the appropriate point.
I'm going to assume here, that what you want Omni, when you think of "harmony", is a balance between diversity and specialization. So I think a good way to achieve this, is to look at how a character might develop, such as Illuminated One's calculations - and parse out typical scores based on 'single stat min-maxing' or 'across the board flat scores with purely harmonic means'. Then in comparing the numbers, alter the math so that the "peak" of a character's ability, falls somewhat in between these scenarios - a mathematical paradigm that rewards well thought out specialization AND diversity.
It would seem you want to do more to avoid having pure specializers than hindering a jack-of-all trades, but by adding bonuses in the appropriate points, you can reward someone for making a couple stats shine, while allowing them to not be utterly crippled if they are deficient in some area. The point being that a player can neglect some things as a matter of choice, because otherwise there is simply enforcement of pure diversity, and no direct reward for ever trying to excel in any one thing.
People are multifaceted, some facets are dull, some are sparkly, but no one facet makes you a god.
