Comparing the specs of the 3-valve V10 that Ford provided in trucks and Class A motorhomes (the less powerful 2-valve V10 was used in vans) and the new V8, I don't see a significant difference in maximum horsepower and maximum torque between the two.
What I do think I see is that: The new V8 develops it's horsepower and torque within a lower RPM range, and that - more importantly for Class C motorhome use - the new V8 probably fits into the cutaway E350 and E450 chassis in the one and only stock horsepower and torque configuration as will be used in all other Ford vehicles with it.
If the above is the case, then the folks who would not use the V10 to it's fullest by rev'ing it ... will be happier with the new V8 in whatever vehicle it's in.