We have dual max-props on our Prout Escale 39'' catamaran. They have been very good to us, although adjusting the pitch on the older models is quite difficult.
I haven''t seen the large price discrepancies previously reported here between AutoProp and MaxProp. Of the two technologies, the AutoProp is clearly superior since it adjusts its pitch for every speed setting unlike the MaxProp that is just as pitch-limited (once set) as the fixed competition.
Thus, my clear replacement choice is AutoProp, should our MaxProps ever fail. Until then, I''ll enjoy the MaxProps as much as I can.