Readability increases but sortability decreases with ddmmyy as opposed to yymmdd.
Readability increases. Dates we use in day-to-day work are probably power-law distributed going backwards with more recent dates being more common. That means if most of the dates will have year 2011, we can guess that, and the day and month become more important. And if most of the months will be current or previous month, we can guess that too and day emerges as the most important piece of info- we will want to read that first. The yymmdd is less readable because it gives us information we (probably, given the power-law distribution mentioned above) already know first, such as the year.
Readability increases. Dates we use in day-to-day work are probably power-law distributed going backwards with more recent dates being more common. That means if most of the dates will have year 2011, we can guess that, and the day and month become more important. And if most of the months will be current or previous month, we can guess that too and day emerges as the most important piece of info- we will want to read that first. The yymmdd is less readable because it gives us information we (probably, given the power-law distribution mentioned above) already know first, such as the year.
But you lose sortability, yeah.