I don't think SDM is available for the SX730, but I see that CHDK is. I want to be sure that I can trigger both shutters using CHDK with a pair of SX730s. Can anyone verify that this is possible?
Yes, I tested USB remote when I did the port. I haven't measured the timing, so I don't know how good the sync would be.
Note this camera uses micro-USB, so cables made for the older mini-USB cameras will need an adapter.
FWIW, you can also use the HDMI port as a remote input, by connecting the HDMI +5v and hotplug detect pins. Unlike the USB remote, this doesn't require an external +5v source.