almost 700MP vs a mortar pit of 400?
Exactly. You have to spend manpower to counter things. You have to spend more manpower if you want to counter things quickly. 2 LEIGS counter mortar pits quickly and require almost no micro to do so. After you killed the mortar pit, you now have 2 Leigs to bombard infantry sections -that have to stand bunched up in cover to be effective- with. I don't know what more you could want. Countering emplacements HAS to come at a price, otherwise there would be no point for the opponent to even construct the emplacement to begin with now would there?