My 2 cents - I have the RRS BH40 and love it. Have the quick release and L bracket for my D70. Although the ball head allows you to go to portrait, the camera is then not centered over the tripod. (Which is true with all the ballheads I have seen)
With their system, RRS allows you to reposition the camera from landscape to portrait in a second and the lens remains centered on the subject and the weight is directly over the center of the tripod.
I don't use any BIG glass so I figured I did not need the BH55.
Yes, it is expensive but IMO, you do get what you pay for - a great system.
I have even shown it to non-photographer friends just because of the precision and workmanship.
Also, the quick release head has a built in level eliminating the need for a hot shoe level.
Did I say I like it
