Well, all I can say is - get to the boss battles and see how many of your archers will die in the first mass attack. This is a good way to discover how your army will fare against them.
Know that the Spider webs your ranged units every time they attack for 2 turns. This means that if you shoot with all your archers, they will not be able to attack and will be immobile for 2 turns. Very inconvenient, to say the least
Please keep in mind that I'm always analyzing from impossible difficulty point of view... I assume that on normal, an archer party may do really well against bosses, because they have less attack, less defense, and less health.