Welcome to the forum Mark.
Roger - would your answer be any different if the two 200A breakers were changed to 4 100A breakers on #4 copper (all from parallel lugs and assume each 100A feeder terminates in a 100A MLO lighting and appliance panelboard)?
If tap rules were followed, any number of lighting appliance branch-circuit panels
can be fed using 310.15(B)(6) immediatly downstream of the service equipment.
If we look at a 30 unit condo, (any number can be used) from the Metering Equipment, and disconnects at this location, the individual feeders to the lighting appliance branch-circuit panel in each unit could use 310.15(B)(6).
Roger
