  We present an updated impact parameter dependent saturation model (IPsat)
determined trough a fit to the combined HERA I and I+II reduced cross section
data. The same HERA data are used to fit the linearized (IPnonsat) version of
the applied dipole amplitude, which makes it possible to estimate the magnitude
of the saturation effects in various experiments. We find that both
parametrizations provide comparable descriptions of the considered data when an
effective confinement scale dynamics is incorporated with quark masses.
Moreover, it is possible to consistently determine the light and charm quark
masses. The role of potentially non-perturbatively large dipoles is examined in
detail, with the result that, especially in case of the structure function
$F_2$, their contribution is numerically significant. Potential to discriminate
between the two models in future $e+p$ and $e+A$ experiments is also
illustrated.
