I think we can take a little from the old format and a little from the new one.
In the old format I thought there was too much time wasted actually cutting tape, opening boxes etc... more often than not I actually skipped that part so I could get to the good stuff (letters, postcards and the items enclosed).
Another point for the new format was that there were more items in the mailbag (which is a good way to get the pile down).
But, I think there should certainly be more than two minutes spent on the more interesting items (unless you plan to do a separate teardown), this is where the old format wins.
EDIT: Maybe come Christmas, you could do a "Santa's sack" mailbag episode where you've pre-opened the boxes and pull the items randomly out of a large sack? I think we'd all love to see you in a Santa hat.