I believe the joke specifically here lies in switching the term "run" as in somehow it is now like a "food run" - though would it still be called a "drive-through"/"in" if you are in a spaceship and you fly through it?
(According to this link, the answer seems to be yes:-)
Regarding the original: unlike a "100m run" the goal was never a specific distance travelled, but rather to deliver the illegal goods without getting caught by the authorities. Hence his smaller ship with a larger engine-to-mass ratio being able to skirt closer to the black holes than the patrol ships dared (tbh they were probably faster in terms of straight-line capacity - loving tinkering only gets you so far compared to highly expensive engines), thereby shaving distance off from the total, was impressive in that context. i.e. yes it was fast enough for the old man, and more importantly it was piloted by a daring captain who would do whatever it took, including risk his own life, to get the cargo where it needed to be, which is what Obi Wan seemed to be really asking.
And yet don't they both have the same crew size? The Falcon also has room in the back, doesn't the defiant just have a cockpit? It's been a while since I last saw the inside of the Defiant.
No the Defiant has a couple decks, let alone its own shuttle bay, and a standard crew complement of 40-50. It is a significantly bigger ship than the falcon in both crew and size.