yeah, its the same heater. The Magnum has a larger heater.
All they did with the PBS was to add some thermal mass. When you look at the PBS tips, they have a small bulged section that doesn't fit into the hole making the tip longer.
There is a J5xx, J6xx, and J7xx series (increasing thermal mass). There is a table on the Hexacon site that shows what thickness boards they are good to use on. The 5 series is 1/16" thick boards.
Frankly, if you have a nice big reservoir of heat at the desired temp, that is all you need. All that fast thermal response stuff is necessary only when you don't have much thermal mass.