Have you been able to get around this problem?
I'm also trying to use two datepickers, one as a "Start Date" and the second one as "End Date", and I'd like the End Date datepicker's "inputDate" and "from" attributes change with respect to the selected Start Date (e.g. the End Date should never be set to an earlier date than Start Date).
Edit: I just noticed this has been discussed in Issues at the date picker's github e.g. here and can be simply resolved by using the Master version of the component, not the latest tagged release (v0.9.0). For anyone wondering how to do this, I used the latest commit on Master:bower install --save https://github.com/rajeshwarpatlolla/ionic-datepicker.git#fada1dc1386843cdb6bac768a8823edae46d28f9