I have a newer Journey and in looking at your PDF I like the Journey capacities better, I have the Cummins 360 and find it more than enough power for my 36 ft Journey. I would think that the 400 HP would be ample and give better MPG. The Journey has more cargo carrying but I have no idea about the weight. I will say the MH heats and cools well and I only have 2 units on the roof I assume they have 3.
All in all I do not see 50 K advantage.
2012 Winnebago Journey 36M Cummins 360
2014 Jeep Cherokee Limited, 37 National Parks
405 Campgrounds, 1961 nights camping since 2009 and 91 K Winnebago miles