Well, I've had the thing now for better than 2 weeks now. My arm is now a lot stronger but my neck has a strange crook in it from hanging the camera around my neck.
The camera is a brute, no question. With the MB-20 and a 50-135 zoom it weighs in at 4lbs 5oz. whereas the F3HP weighs in at a mere 3lbs 6oz. The F3HP seems a tad lighter. My shutter tester tells me that the shutter on the F4 is very accurate, I'm amazed because it is smack on at 1/1000 sec. consistently. (I can't go higher than 1/1000 sec. with the tester.)
My next test will be a couple of rolls of Velvia, which I'll start by underexposing by 1/2 stop and work up to no stop. Maybe tomorrow.