Yes, again, at close focus these lenses are quite amazing. Even the (really fast!) rz 110/2.8 has decent coverage of 4x5 at portrait distances. But I find it a real gift for higher mag macro because it is so fast... even at large mag, you can at least still see something on your ground glass without having to adjust your eyes for 10 mins under a cloth. I mean, most LF lenses that, wide open, only give you f/5.6 or so, and so when you're at 3:1 or whatever, focusing takes a lot of patience and a lot of light.
Incidentally, rb users: the 100/2.8 can be used on the rb if you are willing to hand shutter. It's a very simple operation, you just pull a couple of pins. This operation does not preclude you from using the lens on an rz body.