  Based on Regge-inspired arguments and counting rules, we formulate empirical
models for zero-skewness generalized parton distributions (GPDs) ${\widetilde
H}^{(3)}$ and ${\widetilde E}^{(3)}$ in the iso-vector sector. If a
hypothetical $a_1/\rho_2$ master trajectory is taken into account, we find that
the polarized deep inelastic structure function $g_1^{(3)}$, axial-vector form
factor, pseudoscalar form factor, and lattice data are well described. Thereby,
we use a symmetric valence scenario in which the `spin puzzle' in the
iso-vector sector is trivially resolved. Utilizing a minimalist `holographic'
GPD principle, tying the $t$-channel angular momentum and collinear conformal
spin together, we build skewness dependent GPD models. Confronting these models
with HERMES and JLAB measurements of hard exclusive $\pi^+$ electroproduction
within the collinear factorization approach, we might conclude that minimalist
GPD models are disfavored at leading order. We provide then a set of GPDs on
the cross-over line that fairly describes both HERMES and JLAB measurements.
