The slipper clutch would put me off buying the new one as I've heard it does away with the engine braking, which is one of the things i like about the old one
I didn't notice the slipper clutch on the Speed I test rode and it's not noticeable on my Tiger Sport either. It was very noticeable on the T120 though....
The slipper clutch only "slips" when there is a big difference in road speed versus engine speed, i.e. If you bang it down too many gears and dump the clutch. After that it'll perform normally and you still feel the engine braking as you would with a normal clutch. AFAIK.