Heres the deal.. the trans becomes impossible to shift if its slipping.. even with a overide it wont want to shift... when the clutch slips it binds the trans.. the lock ups cure that problem. If you dont want a lock up I'm sure you can get by with springs alone. a lock up probably isn't needed.. but.. on the same hand. You might need some pretty stiff springs.. if you dont want the hard pull.. go with a lock up and use lower tension springs.
on my stock cylinder bike I wont be using a lock up with the overide.. I'm going to try 6 extra HD springs to start.. if it slips which I dont beleive it will.. I'm going to a 8 plate setup. I'm sure that will hold it.
So it pretty much boils down to if it slips.. do you mind a heavy clutch pull over spending the extra coin on the extra parts of a lock up?
We were holding a 10mil cub with 6 HD springs on a 7 plate setup.
Was this a lil more informative for ya Bob?