My college is currently working with BB to migrate from Self-hosted to SaaS (planned for Jan 2018).
My understanding is that with SaaS there is "live" (5 - 30 second data sync delay) database that is accessible via OpenDB direct SQL queries.
It is the Managed hosted environment which does NOT provide a "live" database access option. In managed hosting a copy of the DB is made available once or twice per day so the data would be 12-24 hours out-of-sync with production in a managed host environment.
I am not sure if you have investigated Grades Journey yet. There are several that have had success with it like Chris Bray and Casey Eubank. We will have to use this of convert or existing SOAP based solution for Grade integration in the upcoming years to move to SaaS where I work.
Additionally, there is Direct Data Access which for SaaS and similar to OpenDB which we use an a MH client which is closer to real time data with DDA versus for us once a day with OpenDB: