Gregorian chant - four lines or five?

I have had a reply to a Facebook discussion, arguing that setting Gregorian chant in modern notation will encourage congregations to sing it. I don't know where this idea has come from that people can sing Gregorian chant more easily from modern notation which they are used to. I have looked to see if there is any research on the subject and have found none. Most people of course cannot read music at all and even those that can, cannot sing from a score but have to learn the tune and use the score just as an aid-memoire - which is what I and the majority of choir members do. I cannot even recognise music that I have sung for 40 years when it is set in modern notation.

If people are not used to reading from musical scores they get used to Gregorian notation more easily - I could not read music at all and began with the Gregorian notation and then MOVED ON TO modern notation when it was required. Gregorian notation is best for beginners, and for those that are used to modern notation it takes about ten minutes to explain how Gregorian notation works.

The point then is that the 4-line notation is 20% easier to read for a start because the lines are further apart and it is easier to pick a note from four lines rather than five. And in most cases one of the lines is completely redundant because Gregorian music does not extend over the range provided a five line stave. It is also the case that people like to decide where to pitch their doh, by agreement between them, depending on the state of their voices and the weather, etc. One the music is written out to a definite pitch, choir directors tend to use that as a weapon and refuse to make accommodation to people's wishes. A further issue is that the Gregorian notation indicates the shape of the music phrases, and so it is easier to recognise music and phrases within the music, that one has sung before.

A further issue is that there are variations in the dynamics of the music that are not indicated in modern notation eg the difference between square notes and diamonds. These are critical to the sound. Without them, the characteristic "wave" quality of the music does not come out and the music sounds flat and boring, which gets it a bad reputation.

That is not all. If modern notation is used, it takes up more space, and also spreads the text out along the lines in separate syllables. It is then no longer possible to apprehend it as text, which is disastrous seeing that it is the text that is important and the music is essentially ornamentation of the text to give emphasis to certain words and phrases.