Hello Miro,
I've been searching regularly myself for solutions to booting the W-30 via SCSI myself. I've had success with getting the W-30 to recognize various HDs, Zips, and MOs, but no success with booting from these devices. I know the W-30 can't boot from a Zip. I also haven't found a CD-Rom device yet that will work with the W-30 either, although I knew they exist. So far, I have found either an MO or Zip drive to work best when loading and offloading files. I also bought a backup disk drive in case my first one fails simply for the task of booting the W-30.
Personally, other than the limitations of sample memory, I think the price of the Roland W-30 would increase dramatically if there was just a way to get it to boot without the floppy drive. Same goes for the Roland S-330. Currently with that model there is no floppy drive you can buy separately. I'd have to buy a whole new unit to replace that drive. Although I haven't tried like you have Miro, I haven't heard of much success with floppy drive emulators either.
I haven't given up though and will promptly post any updates I find on your forum should I find a solution of any sorts.
Thanks very much!
Jim
Note - I did find after much research that apparently using "Apple" drives should increase the chances of finding a bootable device. Currently I am looking into acquiring some old Apple HDs. Would love to get an emulator working though. That would be cool!