To elaborate just a little on the DIR. The Core second stage has an outer retainer screw, the one you can see that holds the purge cover in place. Remove that and you find a second retainer and a slip washer that keep the diaphragm in place. DIR and such of that ilk evolved from cave diving in Florida principally, penetration diving, overhead and significant deco are common. Second stages that can be partly disassembled underwater get the nod over a second stage like the Core that would need a tool possibly to remove the diaphragm to clear debris. The other issue is hose routing. While the Core first stage, IMO, has excellent hose routing for single tank use, the routing is not ideal for twins. And DIR divers are heavy into manifolded twin sets with dual regs. Plus it is AL and not Hog or Dive Rite or Halcyon or whatever. And I am not be dismissive of these things, not at all. Different diving groups have differing needs and the Core was not meant to address that niche of diving. Make no mistake or misunderstanding, the Core is a reliable and top performing regulator.
James
James