Only way to recover was to take the drive to a non amiga and delete the offending data.
Uh, no. You can take it to another Amiga to fix it. You can also disable devices in the early startup menu to prevent the bad filesystems from being loaded. Easiest thing to do is to boot from an OS "Install" disk and use HDToolBox to correct the errant filesystem in the RDB (Rigid Disk Block.) I admit to trashing an RDB or two in my time.
As to the flexibility, my RDB currently contains FFS patched to 45.17, PFS3, and CrossDOS (MS-DOS filesystem.) All related partitions mount at boot and are accessible without running startup-sequence or mounting via Workbench's DOSDrivers drawer. Running OS3.9 and I need to update to 3.1.4, but I have not had the motivation to do so, yet.
I have mounted and used SATA and IDE drives on my 4000 desktop via USB (Deneb.) Never tried this, but I suspect one could also hang a drive off a MorphOS machine, like a MacMini, with a suitable USB adapter. Obviously not with a SCSI drive... though, you might be able to use a USB to SATA/IDE, then SATA/IDE to SCSI.