  The H1 and ZEUS collaborations have recently presented their final results
for the combination of inclusive cross-section measurements taken during Run I
and Run II at the HERA collider. In this contribution, following an overview of
recent progress in the NNPDF framework, we quantify the impact of the legacy
HERA dataset on the NNPDF3.0 analysis, finding that it has a very moderate
effect in the global fit. On the other hand, we also find that a HERA-only fit
using the legacy dataset leads to a rather more accurate determination of PDFs
as compared to a fit including only the HERA-I data. We also explore the
sensitivity of the fit with respect to kinematical cuts in the small-x and
small-Q region, finding hints of a possible tension between data and theory.
