Now that PHD2 can do a full pause (stop both guiding and imaging) the Pause Autoguider on Download makes more sense to reduce USB contention.
For example, the QHY5II-L camera I use for guiding is very chatty. Although I have set everything I can (according to QHY’s FAQ and various forums) to reduce its USB traffic, it still disconnects sometimes if SGP is downloading the imaging camera. I have to reboot the laptop to get it to reconnect. My laptop has 4 USB 2.0 ports but they all are controlled by the same hub, so moving the camera to a different port does not help.
I understand that this option was not terribly useful in SGP 2.3 because PHD continued to image and download even when paused, but this is no longer the case. It would be useful to me and, I would expect, to others.