  Grand canonical simulations designed to resolve critical universality classes
are reported for $z$:1 hard-core electrolyte models with diameter ratios
$\lambda {=} a_+/a_- {\lesssim} 6$. For $z {=} 1$ Ising-type behavior prevails.
Unbiased estimates of $T_c(\lambda)$ are within 1% of previous (biased)
estimates but the critical densities are $\sim $5 % lower. Ising character is
also established for the 2:1 and 3:1 equisized models, along with critical
amplitudes and improved $T_c$ estimates. For $z {=} 3$, however, strong
finite-size effects reduce the confidence level although classical and O$(n
{\geq} 3)$ criticality are excluded.
