Comparison of the total FoM_TOT (top) and dark energy FoM_DETF (bottom) figures of merit for the 3D Fourier-Bessel analysis (horizontal dashed lines) vs. tomographic analysis (solid lines) as a function of number of redshift bins. The upper lines (dashed and triangle) result from assuming a fixed bias, the lower lines (dotted and circle) are obtained when assuming a grid of 5 × 5 nuisance parameters in scale and redshift described in Sect. 3.1.5.