With an 07 he should have the gen 3 engine with the highest output V10. One might be your perception here, what did you come from before this? Last MH we had was 460 with 3 speed, our 06 V10 5 speed is a race car when compared to that! However compared to my 323i convertible it somewhere between turtle and snail! :)
Some have stated that Ford has pulled most of the capacity out of the V10 in Gen 3, starting 06 model year chassis, and even Banks when I talked to them said the improvement wasn't as drastic as with previous years.
In my case I will generally let the trans shift itself and hold the throttle to not exceed 4K, it will speed up if I let it climb to 5+K but the fuel consumption climbs much faster than the speed! :B I am not in that much of a hurry these days and tend to try and speed up some before hitting the bottom of the hill.