On the 1.5A rail (2.2A ILIM) there is a 3.3A saturation current inductor. Would an estimate of headroom not be sufficient?
Yes, a headroom estimation would be good, but it comes at the cost of the size of this inductor. Depending on the application, if you have low output current for most of the channels then inductance values, lower saturation current levels and smaller packages are preferred. This peak current protection may prevent you optimizing the inductors for your application.