Actually I didn't find it hard at all to make a 'difference from requested time'. I am hurrr sometimes.
But the sort by headers function is broken for the search Travel Time Search.
The form is like: Hours[ ] Mins[ ] +/-Mins[ ]
and it uses whatever home coords you're currently using on the map to search.
I also added an 'age' table so you can sort it by days old for BP harvesting.