A grade 4 is a C and you won't have to retake if you get a 4 BUT some universities and sixth forms (I know one I applied to does) expect a 5. It was in the news recently actually so you might want to read this as they explain it better than me: http://www.bbc.co.uk/news/education-40418457 Hope that helps
your statement is true but when u say low C for 4 and 5 is a good pass it confuses people as its not low C anymore its standard so its not a minus but an equals and some unis like queen mary think a 5 is a B when its not it a 6 is a B which means a 5 has the same value the old legacy B grade does
There's a lot of confusion over the new grading structure as DoE says this: Grade 4 (Standard Pass) - Low Grade C Grade 5 (Good Pass) - High Grade C/Low Grade B
However, I would play safe and say Grade 5 is the pass grade.