Someone I work with was planning to use USB OTG to interconnect a number of Pi zeros but he was running into low performance and sometimes crashes with various configurations.
I decided to try testing using the ethernet gadget with iperf, running the iperf server on the host pi 0 and the iperf client on the gadget pi 0. The performance reported was abysmal and I frequently got kernel panics from the host pi zero. I tried upgrading the host pi zero first to the latest packaged kernel/firmware and then to the rpi-update kernel/firmware. That seemed to reduce the incidence of kernel panics but not eliminate them.
Anyone else seen anything like this?