I'm not shure, bur maybe, the S1100 (v4.3) can only read S3000 format via SCSI (and not via floppy ) ?
I have no problems to read programs made on my S3200XL on my S1100. I only tried SCSI, both Zipdisk and CF cards. I have no floppy drive in my S1100 anymore, so I can not test this.
Also I have no problems to read S3000 CD-roms in my S1100 via SCSI