We had the first dolby A units in our studio in chicago. After several months of use none of us liked them and stopped using them. Most studios instead went to 30ips recording
The same was true for Dolby Surround films. They actually used Dolby-A on the L/R optical tracks on top of a second layer of Dolby-B or C (can't remember) for the decoded surround channel.
However! Based on my experience this was not on the encoding but the decoders. We used our own decoders instead of the Dolby-A cards and they had the best of both worlds. Low film noise and open/airy/immersive top end.
I suspect it should be possible today to build up an unofficial Dolby-A decoder digitally which is just as good.