The T-12C was a sought-after unit for flying around the Australian bush. Generally, it locked on to the NDB at greater range than many other (even newer) units. When I bought my first aircraft, a C150F, I was delighted to find a T-12C, even though it was an antique by the time I acquired the aircraft in the 1980s. With only standard tanks on the very modestly equipped C150, a sensitive and reliable ADF able to tune both AM broadcast stations and NDBs gave me a tiny bit of redundancy in the often challenging bush VFR navigation task.
In answer to an earlier question, the 'CW' setting on the Bendix is essentially the same as the 'BFO' setting on some other units. Both permit the accurate tuning of the AM carrier, or the reception of keyed CW (morse) transmissions. There's a bit more to it than that in terms of the history of direction finding, but for most pilots that's close enough.
The aircraft in which I did my initial training also had a T-12C (it having been retrofitted to replace a hopeless Cessna ADF). In that situation its main use was to allow the CFI to listen to the cricket whilst inflicting navigational pain on the student.