It's not that simple. Depending on what type of fight you are in, having less men can be an advantage. If you are in an equal fight gren vs con, both squads have the same amount of health, yeah? So that means each individual gren model has more health than each conscript model. This means that it is much more likely for a conscript model to die first, and lose overall DPS.
Of course, lower squad sizes make the unit more vulnerable to AOE and snipers.
