"...when you're done with piling all these pure interval fifths on top of each other is 24 cents sharp of the C you started out with..."Mathematically this may be true, but your issue is only worth a penny less that two-bits as it manifests seven octaves apart, which *nobody in their 'right minds' will be juxtaposing for its fullest effect... let alone be able to discern it.
The tuning adjustments are done at a smaller intervals and more accurately by ear by listening to a combination of ratios or a more complex ratio (such as 5/6 instead of 2/3), or so it is to my ear...
On the note of different keys have different characters: A piano's sounding board and stringing has
also had a lot to do with the character of key centers. The b natural (or b flat depending) below "mid" c is the point at which the note on a piano changes from comprising of three tuned strings to two tuned strings per note. This has a clear effect on how we (for example) relate c-major and a-minor (keys which share the same notes, but not the same "resting" point). This effect of
timbre is minimized by correctly tuned instruments of the finest caliber... but how many of those are out there?
