The 40 in our boat might have been a one off experiment by the good folks at Ranger Tugs to see what it would do.Not having run a 30, I'll have to go with their word that its only good for an extra knot or so. Anyone who is hoping it will jump up and outrun a C-dory has probably bought the wrong boat. Probably its strong suit is that it will do much the same as the 30 while working a little less and holds its immense speed under heavier loads. I have run it up a couple of 9 knot tidal rapids ( Boat pass off Saturna Island and Malibu rapids at Princess Louisa Inlet) and it certainly punched its way through comfortably. Having said that ,I would certainly want to try them both before I spent extra pesos on the larger motor.
Like I said, it was an existing package, and we are very happy with it.
Cheers, B.C. Bruce