Hi,

I did buy  a RB a few months ago and love it. It is huge and it might be
archaic, but the look of a well exposed pin sharp velvia 6x7 slide makes
it all more than worthwhile.
I use the camera mainly for portrait and close ups. For me the extension
tubes are must-have, together with the biggest grip available and a very
big and heavy Gitzo tripod. For lenses I use the 90 (came with the
camera, the 127 will also do for me), the 150 soft focus and the 180.
The whole set cost me well below $1000 and has already paid for itself.
I shoot quit some stuff for magazines and therefore the rotating back is
ideal to get a lot of portrait oriented shots without having to turn
around the whole camera. Very smart design indeed.
The RB system is very cheap at the moment and very available, the RZ's
are more expensive, especially the lenses are not very common
secondhand. You can use RB lenses on a RZ but it seems that you lose
some functionality.
Go for it.

Michiel Fokkema

Start with the std. 110mm lens.  It works very well for a wide variety
of subjects.  If you need longer lenses, the 180mm W-N is nice.  Shorter
optis?  The 65mm L-A is incredible.  And a couple extra film backs will
have you set for life.

Bargins abound.  Shop carefully and you can get an entire kit for very
cheap.

- Chris