>>The one real problem metric has is Time. Yes, there are ways to measure time in metrical units, but not so easy to do - and we already have so many various calendar systems around the globe...
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>The official unit in SI (Système International) is the second, but it is not customary to express time in Megaseconds, for instance... BTW, the second used to be defined as 1 / 86400 of a day, but it is currently defined independently of a day. This means that if days gradually get longer, "leap seconds" have to be inserted.

Yes, that was the simplest form I was thinking of, the second - but how constant is it truly, inside the second, for one point? And the second point is the one you make, about needing to adjust seconds.

Probably the second is constant enough for most things, I guess, but still, who wants to express a calendar date/time in terms of 123456789^^23 seconds from some consensus beginning-point? <g>


>Another problem I see in SI is the definition of the kg. (but this doesn't affect the end-user much). Second and meter have been defined in terms of fundamental constants, but for the kg., a "prototype" is still used for the definition.

Good point - yes, the kg is very arbitrary by humans, unbased on anything constant in Physics theory.