The problem with high gain amps with lots of bells and whistles is that they are very complicated and wire dress has to be perfect to keep hum down.  I haven't looked into a 5150 schematic specifically, but some...say...like a Bogner Ectasy would be nearly impossible, and cost prohibitive, to make a hand wired version of.  Most high gain amp offerings I see clones of a single channel and often are streamlined even more to make it a little easier on the builders.