The “new” Seiko 6L35 caliber introduced in the Presage SJE073J1/SARA015, or is it?

So at Baselworld 2018, Seiko introduced a new Presage model. The international model name is SJE073J1. There was a fair bit of fanfare to this model because of the “new” caliber 6L35 that powers it. It promises to be slimmer …