Various user setable VarVals with which to tune proceedings:

USB$PowerDownTime      default 200(ms)   Min power down time for a device to
                                         correctly reset device

USB$PortPowerUpDelay   default 300(ms)   Min time to wait whilst device powers
                                         up

USB$PortResetDelay     default 100(ms)   Min delay whilst a device is being
                                         reset

USB$PortStartupDelay   default 100(ms)   Delay after port fully powered up, and
                                         after issuing port reset command