Recover old floppy disks

I've tried the -d and -b options of ddrescues and I haven't succeeded.
I've installed old Linux distros like opensuse9 and ubuntu 10.04; some actual BSD versions FreeBSD, openBSD and dragonflyBSD; and Solaris 11.4 without success. Finally, I've sinned and I've installed Windows 7. And it works! To keep my soul cleaner I mark Windows 7 as abandoware .
The floppy disks that only contain files I copy the content to the hard drive. The ones that are protected or with error sectors I use disk2img /t80 /h2 /s9 /a5 /i to create an img file. I'm wondering if this img file can be opened using openMSX.
I've tried to run RuMSX or disk-manager for the protected ones but they can't rescue the floppy disk or create a dsk file.
Is there a better option to dump protected floppy dsks from PC?