"I follow only occasionally the discussion but Daniel Kinzler wrote "Go back to using MediaWiki's DB abstraction for running queries" and "we could have implementations of the query interface based on MW's DatabaseBase" [0, 1].
Taking into account the experience gained from the SMW SQLStore implementation (which is far from optimal and has several serious issues) using MW's DatabaseBase showed limitations such as:
- DatabaseBase doesn't allow DB type agnostic queries (you always have to cover special cases for either sqlite, or postgres
- DatabaseBase has no sufficient (+90%) test coverage for any of the three available adapters mysql, sqlite, and postgres
- DatabaseBase has no interface but instead uses an abstract class as definition which means when creating a mock you work with an implementation focused and not with an interface object
- MW's support for postgres is insufficient and has several open bugs
If because of WMF's policy  "the WMF would require a line-by-line review ... This is not feasible.", DBAL is not an option I would advise against the use of DatabaseBase and instead look for an option where PDO is used as abstraction layer. 
 http://wooptoo.com/blog/pdo-vs-mysqli-performance-comparison/ "