Great feedback @amoghe. If this was a full LDAP as a Service, which synced with Google Apps, rather than just an LDAP adapter, would that make sense?
What we are/were looking for is a service that could provide LDAP "frontend" to Google Apps identities so we can have a single set of credentials across services (and email etc).
Seeing as how nothing of that sort exists, an LDAP(aaS) would also suffice, but not be ideal because: (a) we would end up using only a small subset of the LDAP functionality (namely auth). (b) seeing as how none of the early engineers have administered a (full blown) LDAP service, someone would have to climb this curve.
I'm curious why cloud based identity management solutions don't offer this (eg. okta). However I wont claim to know/understand the full breadth of their offering and whether this aligns well with their business.
AFAICT both OneLogin and Okta do not provide LDAP-like access to their identity service. Unfortunately we're running a couple of services that authenticate using either LDAP or an internal user database. We're stuck using the latter option (for now).