I don't know how compatible the Fujinet is re disks and cas files (hopefully. very in your case Richie). If you ever want the most compatible way then get yourself an AVG or SUBAVG cart with the SIO cable. Not looked at what the SUBAVG can fully do. But my AVG run's everything I've thrown at it over the years. Not tried anything lately but I reckon it will be sound as a pound. Then again, if the Fuji is doing all you need, then the AVG would just be an unused extra..The other nice thing that the AVG etc give is an onboard RAM upgrade.
Yeah the old FujiNet can emulate 8 disk drives and run xex files. The cas file playback is pretty solid. With the that and the Side 3 cart I’m pretty much covered. I did like my original AVG cart though. Just had to replace the battery on my U1MB today which isn’t great given I’ve only had it a couple of years.