I have made enlarged negatives with Bergger Orthochromatic film BPFB 18 and, as for Aggie's process, you can work with a darkroom safelight which gives you more of a feeling of assurance as you can easily see what you are doing. just like making an enlargement on paper. Once you have your "flattish" positive you have the choice of using that to make negatives of differing nett densitiy ranges to suit the requirements of the processes in which you wish to make your alt.process print. I would like to try Sandy King's method but I do not, at the moment, have a colour printer.