The burning and duplicate utils can burn to +/- DVDs both R & RW and can burn to + dual layer disks. I use SmartFileSystem for storing the ISO images as you need a filesystem that can cope with ISO files bigger than 4Gb.
I thought that the file size limit on AmigaOS 3.x is 2GB independently of the file system and device driver you use, because the limit is also imposed by the dos.library. Isn't this true?