In reply to dsherlek:
Usually the thing that is not preferred is having a monitor affects the stimulus to the DUT.; monitors are supposed to be passive. And depending on the block to system level reuse that you need in a agent (i.e. if the driver is turned off in a passive agent), a monitor should not depend on the driver for the monitor to function properly.
But sometimes a driver depends on a monitor to function properly. So either you duplicate the functionality in the driver (also not preferred), or let the monitor feed the driver, which is probably your best option.
