  We confront saturation-based results for diffractive $\psi(2s)$ and $\rho$
production at HERA and $J/\psi$ photoproduction with all available data
including recent ones from HERA, ALICE and LHCb, finding a good agreement. We
show that the $t$-distribution of differential cross-section of photoproduction
of vector mesons offers a unique opportunity to discriminate among saturation
and non-saturation models. This is due to emergence of a pronounced dip (or
multiple dips) in the $t$-distribution of diffractive photoproduction of vector
mesons at relatively large, but potentially accessible $|t|$ that can be traced
back to the unitarity features of colour dipole amplitude in the saturation
regime. We provide various predictions for exclusive (photo)-production of
different vector mesons including the ratio of $\psi(2s)/J/\psi$ at HERA, the
LHC and at future colliders.
