on amiga as on every other platform at least a basic driver for a bootable device needs to be available at boot time, before that device needs to be accessed. on pc the drivers are in bios. on amiga in kickstart. except you have some bootable flash solution to keep your kickstart and extension modules, like deneb, you need to boot from a device supported by the genuine kickstart, likely ide or some autoconfig extension/card and let the system restart to access further devieces.
what concerns adaptec scsi pci, this is afair a third party development in an experimental stadium, a proof of concept, if you will. data transfer is very low, even in comparison to the devices available then. it wont suit you except the dev was still around and willing/able/open to improve this.
