Charginos and neutralinos (and LSP): Kinematic limit reached after 30 pb-1. So the recommendation is to deliver at least 30 pb-1 at the maximum LEP energy.
Scalars (squarks and sleptons): Luminosity is important. Every increase in Ecm of 2 GeV is worth if the reduction in luminosity is less than 60-80% (depending on the channel). The total improvement in sensitivity would be anyway small; for example for the stop to charm chi topologies an improve of 1 GeV in the stop mass discovery potential would require at least 25-60 pb-1 of Luminosity at 206 GeV. An improvement of 2 GeV would require at least 120-200 pb-1 at 206 GeV.
In conclusion the gaugino sector requires at
least 30pb-1 at the maximum energy. The scalar improvements
are expected to be small and they require large luminosities: change in
Ecm is worth if : {(dL/L)
/ (dEcm /Ecm)} > [-10,-20]
(the range depends on the actual sparticle/topology). The optimization
of year 2000 running should be more driven by gauginos
rather than by scalars (due to the small expected improvements).