The War Horse HMG/Super-HMG will be an invaluable asset for defense. The firerate is better than any autocannon, even though it's still slow. The M2 Browning wasn't exactly doing Hitler's Buzzsaw with 1000+ RPM, after all. It was relatively slow-firing. But when the enemy realizes that your average full-grown tree
doesn't provide any cover, infantry assaults are going to go to a standstill. Plus, it will give us additional guns on the line----it supplements the autocannons, not replaces them. It is meant to be mobile, portable in, say, three-man teams (Two guys lugging the gun and some ammo, one with the tripod and a lot of ammo), or two-man with the cart.
http://14544-presscdn-0-64.pagely.netdna-cdn.com/wp-content/uploads/2013/04/maxim_crews.jpgThat image is about what I'm thinking of. It's probably slightly upscaled from that, but with a bit of modification that cart, can carry ammo as well. IRL, the cart can be moved and used by a 2-man team and carries a .50 cal Russian HMG.
We're not automatically adding the things onto aircraft. Unless it adds no difficulty. But think about it: This is going to be, at most, Normal difficulty. It's a gun, been in production for decades, that we understand. Not to mention, it's hideously outdated and doesn't use modern advancements, making it easy for a modern engineer to say "Oh wow, we can just do this and this like our LMG/MMGs and this like the autocannons and BOOM, it's better". We have a lot of engineering basis for keeping weights down (On the autocannon, I believe) and also for higher firerates (Sorraia) and all of that fun stuff. Anything else is tempting fate with the difficulty.