Calabim are generally known to be about the most overpowered race in existence. would anyone disagree? Between the manors, a champion and berserker UU with acess to two of the best spellspheres, vampires with essentially infinite experience , without having to fight anything and a neat +10% base strength as well as faster healing, the ability to give said vampirism to any unit of lv6+
not to mention a powerful suicidal axeman unit, an immortal with Channeling II and acess to 3 differrent spellspheres, an additional granary which is one of the VERY few buildings that give a straight amount of food
that said, everyone loves vampires. They have that romantic allure. it's easy to see why the team wanted to allocate them so much power, and why they'd be averse to reducing it.
it's difficult to strike a balance between doing them justice, and making them overpowered.
Slightly off topic, I'd like to see sun magic have more effect on them, like Sun II doing damage and causing a temporary strength penalty, as well as stunning.
but anyways, halving the production bonus from manors seems a bit much. I'm thinking if it's going to be reduced, it would be better to reduce it by a relatively small amount first, and then reduce it more later if it proves necessary. -50% is a LARGE reduction, no mistake about that.