I'm seeing the same issues, drop offs in reported hashrate, some devices not seen when started, some going dead after a few minutes. Review my post above for a temp solution until BFG 4.0 comes out. (sorry Linux only)
Have you tried BFGMiner on Linux? Your above post indicated that you downloaded a Windows build, had issues, switched to a different app and Linux and had success. It may have been the switch to Linux, not the switch in apps.
I am currently the one working on the GridSeed support. While BTC and Dual Mode support are still planned, I'm not seeing any issues like you have reported. On the other hand I am not testing with 10 and 20 and 40 devices, only a couple and both from the same reseller.
Basically there is no "until 4.0 comes out" as there is nothing yet planned to address these issues. I've got a couple of these running for days at a time on Windows with no drops in hashrate, no issues discovering them, etc.