as a professional musician ,I will give some examples,sometime around 1985, I played Sidmouth folk festival, folk on 2 were recording in the beach hut, I sang 3 songs that were ecorded on folk on 2, in the interest of musical balance i sang 2 trad songs and one original composition, for my own composition i received 100 pounds royalties[ this was in 1985], for the 2 trad arr songs i received about 5 each. if i had benn money orientated i would have sung 3 of my own compstions and received 300. BrianPeters is a singer who sings mainly trad material, for a singer song writer it is completely different, as it is for someone like myself who sings both.
for the record I never fill in live performances at small folk clubs, but for radio performance i certainly do, and when requested by festivals i fill in prs sheets.
as i have said i have criticisms of prs and imro, but it needs to be taken into consideration what these organisations do with their royalties, they do put some of it back into promoting creativity via workshops etc, in my opinion not enough and too much is spent on bureaucratic adminstration and glossy brochures, i would be happier if they gave more money to promoting workshops etc and more money to the people who do the creative work ...the songwriters.