29Eogan, George, and Eoin Grogan. "Prehistoric and Early Historic Culture Change at Brugh Na Bóinne." Proceedings of the Royal Irish Academy 91C (1991): 119.
Here is the authors' argument for positioning the Paschal Fire event at Brú na Bóinn rather than the Hill of Slane:

"Slane is not specifically mentioned in the early lives of the saint, although it appears that on his return to Ireland Patrick landed on the east coast. Muirchu, in his Life of the saint, states that the landing place was Inver Colpa, the mouth of the Boyne, and that from there he moved inland and in the evening arrived at the 'burial place of the men of Fiacc' where he and his companions pitched their tents and celebrated Easter (Bieler 1979, 85). Could this have been Brugh na Boinne? It is, indeed, possible because of the reference to a burial place and also from the political point of view. There is no archaeological or historical evidence that the Hill of Slane was then an important site, but there is evidence, as already mentioned, that Brugh na Boinne was. One could then speculate that it was at Brugh na Boinne, not the Hill of Slane, that St Patrick celebrated his first missionary Easter in Ireland. Amongst the sites in Brugh na Boinne, Knowth has the best proven evidence for settlement, possibly as the home of a prominent family. As is known from historical and anthropological sources, it was usual for a missionary to approach a local chieftain and, if such existed, Knowth is the best candidate as the site of his residence. It is likely that Slane only came to prominence as a result of the establishment of Christianity, as a counterbalance to pagan Brugh na Boinne, as an attempt to minimise its importance, even to replace it, or at least to provide a Christian alternative to paganism. This could have led to the decline of Knowth and a corresponding growth in the importance of Slane which became not only an ecclesiastical site-St Patrick appointed Erc as first bishop-but likely a political one also."

The Heritage Guide to the Hill of Slane seems to come to a similar conclusion: "Cathy Swift has shown that the antiquarian James Ware linked Fertae Fer Feic with the hilltop, although sources suggest that this place may have been elsewhere along the Boyne Valley. Swift stresses, however, that early medieval mounds, churches and forts were often connected with legal centres. The Hill of Slane contains both an enclosed mound and an important church site documented as an important legal centre from the eighth century AD, with links to French monastic sites. Therefore, while Slane is unlikely to have been the site of the legendary paschal fire, it has important links to the Patrician story." (Seaver, Matthew and Conor Brady. Heritage Guide 55: Hill of Slane. Dublin: Archaeology Ireland, 2011.)