Icelandic dative-nominative constructions exhibit a syntactic hierarchy effect known as the Person Restriction: only third person nominatives may control agreement. In these constructions, there is variation between speakers in the extent to which the verb agrees with the nominative for number. Sigurðsson & Holmberg (2008) explain this variation as arising due to differences between varieties in the timing of subject raising, using a split phi-probe. This paper revises their approach, using the feature gluttony mechanism for Agree developed in Coon & Keine (2020), and a split phi-probe in which person probing precedes number probing. Within this framework, the observed variation can be captured by allowing variability in two independent parameters: the timing of EPP subject raising, and the visibility of a number feature on dative DPs. The proposed mechanism describes the variation, including predicting the observed optional agreement in certain cases that previous literature had struggled to account for, and makes additional predictions about the differences between varieties in cases of syncretism within the verbal paradigm. An investigation into these predictions should allow this already well-studied area of Icelandic grammar to continue to be a useful test-case for crosslinguistic assumptions about the mechanism of Agree and the status of dative arguments.