  In view of the recent high-statistic KLOE data for the $\eta \to \pi^+ \pi^-
\pi^0$ decay, a new determination of the quark mass double ratio has been done.
Our approach relies on a dispersive model that takes into account rescattering
effects between three pions via subenergy unitarity. The latter is essential to
reproduce the Dalitz plot distribution. A simultaneous description of the KLOE
and WASA-at-COSY data is achieved in terms of just two real parameters. From a
global fit, we determine $Q=21.6 \pm 1.1$. The predicted slope parameter for
the neutral channel $\alpha=-0.025\pm 0.004$ is in reasonable agreement with
the PDG average value.
