Bingo, at least 1mm. Bear in mind that the top of the positive terminal will become concave over time which may reduce your safety margin. Also if your atomizer 510 is adjustable, it may become shorter after you take the atty off and on a few times.
This type of connector is completely unforgiving of complacent use.
In my opinion the advantages are ~ reduction in device length, cheaper to manufacture, easier to maintain. These types of connector are often marketed as having low voltage drop. Obviously this depends on the specific 510 connector, but compared to a good one the reduction in voltage drop is negligable.