The 'court tombs are the oldest' issue is one that will stay for a while yet. The radio carbon dates for Carrowmore are from the 1990's and most people still use Evans' book from 1961 as their source of info (even if they used a different book, the book they used would have used Evans).

Apart from accademic papers not many books have been published about Irish sites since the Carrowmore dates were established. The court tomb at Primrose Hill gave a date of circa 5400 bce and was the oldest for a few years (Primrose Hill is on the slopes of Knocknarea).

A lot of the dates given for court tombs aren't that reliable due to the times they were excavated (in the 1930s mainly) and so I think these could also get pushed back a little. Most of their dates are comparative and not scientific in the modern sense.