I've been looking through some old threads and reading up on the Cleveland Niblick and from what I can tell it is a very polarizing idea and club. Either someone totally agreed that it was a must, or someone strongly suggested that its a waste of a club in the bag and can be replaced with a good wedge.
I have in my bag:
Driver - Walter Hagen MS2 (10.5*)
3W - Walter Hagen MS2 (15*)
5W - Wilson Staff Fybrid (18*)
4H - Walter Hagen MS2 Hybrid (21*)
Irons - Callaway Diablo Edge-R Steel Shafts:
GW - Cleveland CG16 (50*)10 Bounce
SW - Walter Hagen MS2 (56*)
Putter - Titleist Dead Center Bladed
I can easily take out my 4H and put in a 42* Niblick. That way I still have my wedges but I have something more reliable around the greens and on the fringe.