You can figure an approximate 30% loss of power when you are running a pump i.e. 150HP powerhead = 105HP at the pump. As far as what is perfered it depends on what you are going to use it for, salt chuck and big rivers like the Columbia, lower Chehalis, lakes etc. prop. For use in the above plus rivers with skinny water no doubt a pump. One thing I will say is if you chose a pump make sure that you buy enough HP, the biggest complait I have seen on these boards and from my own personal experiance is to little power = powerhead rebuilds!!!
Good luck and tight lines, Jeff