Currently, the GUI shows the time at which the transaction was first seen. If the user had the client closed at the time of receiving a transaction, it will show the transaction as having the date of opening the client instead of (approximately) when it was sent.
Showing the date of the block may be more useful in these cases. The smart date is (as I understand it) the earliest time that the transaction was seen, so if it is in a block it will show the date of the block, if it is not yet in a block it shows the first seen time.
I'd like to change the date column to show the smart date. Any reason to not do this?
From the point of the UI code there is little difference, except that the nTimeSmart can change and the nTime is fixed at creation, this may be something to be wary of but is no big issue...