In reply to ollyroberts: In all such discussions a quick look at Martin Moran's Scotland's Winter Mountains is worthwhile:
Grade - IV-V
'Friends' - 3 or 4 of sizes between 1 and 3
That advice is as sound as ever. It is obviously WC Tech friend sizes but would translate 3 or 4 of the sizes between 0.5 and 2 which is pretty much what I'd have said anyway myself.
Just for completeness here is what he suggests as a complete rack for IV-V:
Rocks - 1 set from size 1-9
Hexes - Size 7-9
'Friends' - 3 or 4 of sizes between 1 and 3
Pitons - 6 to 8 of assorted sizes
Slings - 2 long, 3 short, 6 extensions, 3 tie offs
Ice Screws - 1 drive-in [i.e. Warthog]
Karabiners - 15-20
I might carry fewer pitons, but overall it is pretty close to what I carry.