I've always thought that if we are redefining time units a better solution might be 100000 metric seconds in a day (making them a bit shorter than the existing

I've always thought that if we are redefining time units a better solution might be 100000 metric seconds in a day (making them a bit shorter than the existing 86400 in a day) and otherwise the same relationships you've suggested: 1 metric minute = 100 metric seconds 1 metric hour = 100 metric minutes 1 day = 10 metric hours.