I’m both a PADI and SSI instructor, so I can speak to both. A dive shop switches to SSI really for one reason, SSI focuses and pretty much requires each diver to buy all their gear from day one! Since a shop doesn’t make their money on classes or travel, you can see the appeal. Also as a SSI instructor you MUST be associated with a shop, there are no independent instructors in SSI, so the shop can take away your instructor cert anytime they want to, so they have total control over you. So for a LDS it’s a no brainer! As an instructor! PADI is by far your best option!