The reports over on the Ford FE forum are that the pressure fed solid roller lifters extend the useful life out by roughly 50%. What that means is that instead of the 3000-5000 miles you get 7500 miles before you need to pull them. I'll see if I can find a thread on that for you. If you don't like the idea of changing your lifters out in another 5000 miles or so then you should go solid flat tappet. Once you get past the break-in, and put a thousand miles on them, they will last the life of your car.
EDIT -- Here's a thread, and darned if it isn't our own Brent Lykins quoting 7500 miles for PF solid roller lifters.
http://www.network54.com/Forum/74182...th+roller+cams