Definitely a fair question.
My thinking was the following: with its additional payload bay space, the DDGH type is always going to be the preferred platform for littoral operations. It is my understanding that blue-water operations tend to favor lower frequency sonar operation, while such systems cannot be fully exploited in shallower waters closer to shore (and there are other factors that make the LF set actually
bad in constricted waters). The CG thus should receive the lower-frequency set.
Note that I originally specified a Spherion derivative, but that's definitely out of date with the capability creep of this drawing. I'll need to rethink the dome size, but I'd like to shift the smaller set to SQQ-90 (with the SQS-60 MF set), which is the system used on Zumwalt.
As a point of size comparison, Spherion is 1.4m high and 1.2m in diameter. SQS-60 appears to be about 1.5m high and 2m in diameter (
here is an image of the transducer; I have scaled from a man who is 1.75m tall). SQS-53's monster of a transducer is 2m high and 4.5m in diameter.
In any case, I get the impression we're caring more and more about towed array performance, and that will be agnostic to dome size.