I think £700 is a bit steep to fit also,is the diff not in a separate housing,i.e remove drive shafts,half moon casing and lsd will be no more wider bulkier than normal diff,nothing to do with gears or cluch packs!!! Dont get me wrong,big job,just emagine your diff goes,its not a total new gearbox,DSG or Manual,manufacturer's make them so they can be replaced indervidually,and a quaife lsd is more complex than standard,but built to the same size.
My Gsxr K51000 has a slipper clutch as standard,although you can buy a off the shelf slipper clutch for many bikes at a cost£300 i think,ie Gsxr k41000,but you dont have to buy a new gearbox/clutch.
Dont be ripped off hurdy,but get one!!!!

Chris.