I had another look at the above procedure with a view to eliminating any problms and/or errors that might crop up. Also of course it would be useful to reduce the size of the resulting ISO so that it would fit on a single layer DVD.
Here is what worked for me ......
rip the main title to one large VOB file using the vobcopy command
vobcopy -b 7.5m -l -i /dev/sr0 -f -o /media/Data/DVD/
Using Avidemux - drag and drop the resultant VOB file into the window.
It will ask that you select the main audio track. It had the correct one selected for me, but it did note that there was an audio offset. So take note of that offset.
Down the left side of Avidemux select
Video - copy
Audio - copy
Format - MPEG-PS (A+V)
Under the Audio section, tick the "Shift" box.
The Audio was -1200m/Secs when I selected the main track, so I entered +1200m/Secs here to account for that.
Now select File - Save - Save Video ...
{I did not bother, but it is also easy to cut from the file any intro not needed, and also the long ending, usually just with music and credits. This would reduce the file size being used and allow for a little more quality of the end result. I doubt it would be noticable, but you never know}
The file this produces should have been reduced to fit on a single layer DVD (4.3GB), and most importantly of all, should be DVD Video compliant.
Now this file can be fed into DVDStyler, which will detect and accept the validity of the compliance of the file, and thus not have to demux & remux it again.
This makes the DVDStyler process very quick indeed.
You may choose to add a menu (or not) in DVDStyler.
You may choose to output to a DVD Fileset or have it produce an ISO.
Either way, the result should be as good as one needs for a back up of the original DVD and will fit on a single layer DVD media.
Again I remind anyone reading this to ensure they have the right to make a personal copy of the work before embarking on this.
regards.