Working in the travel sector we (and many of your clients) have 3 keys dates, which are:
Booking Date (This is standard date in Adobe Analytics).
Checkin Date (The date of the start of a Car Rental / Hotel Stay / Flight / Holiday / Cruise etc)
Checkout Date(The date of the end of a Car Rental / Hotel Stay / Flight / Holiday / Cruise etc)
which creates 2 key metrics for the business
Lead Times (The date difference between Booking Date and Checkin Date)
Duration (The date difference between Checkin and Checkout)
Currently we (and all of the people in our industry) capture Checkin and Checkout using evars. We export this data into SQL and Qlik / Tableau when we want to manipulate it however this is not ideal. Whilst we can easily capture the metrics as events using our data layer it creates an issue where if a customer places 2 bookings in 1 visit or refreshes the metric does not work (both are common).
If Adobe allowed an evar that used Unix time format to allow it would be a huge benefit to us as it would us to keep our analysis inside of Adobe.