Total S/N (black lines and coloured contours) for distinguishing the MHDEC and MHINC reionisation scenarios using the z = 7 21cm–LAE cross-power spectra as a function of the survey FoV and the minimum Lyman-α luminosity, L_α^min, shown for spectroscopic (left), grism (centre) and photometric-like (right) surveys. The 21cm signal noise is computed assuming the SKA-Low1 AA4 antenna layout and an optimistic foreground model. Black and grey stars mark potential LAE surveys at z ≃ 7 that could be cross-correlated with SKA 21cm data (see also Table 1).