Just finished a hilarious hun game on deity, normal speed, standard size lakes map.
Only had room for 2 non-garbage cities (cap being one of the two).
Went tradition to make them as good as possible, switched to authority after 3 policies.
Only two cities meant I could not support a large army, so the early game was all about fighting out in the open, not attacking cities, building up xp, and gifting captured units to CS left and right, and grow grow grow my two cities.
Only had 2 horses in my borders, and was surrounded by CSs, closest neightbor being behind 3 of them, and a wall of jungle too.
Point is, far from ideal conditions for huns.
However, I managed to ally half the CSs by medieval, with Siam on the map no less. Three CS were militaristic, and together with the kill bonus from authority supplied a large chunk of my science. By the time chivalry came I could support six mounted and six melee horses, plus some random captured/gifted garbage, and that was enough to smash one AI who I was fighting for maybe 50 turns prior to that.
From then on it's smooth sailing. Big cities supported by happiness/food/culture/science from CS means you're making way better science than a standard war civ. I got to landships before ANY AIs even had fusiliers. One AI just beelined for labs, so I guess they could have had better units if they wanted to, but there's no way they could stand up to landships with 250xp, who are also supported every turn by freshly captured meatshields.
Huns are secretly a diplomatic civ, it's SOOOO easy to keep all CS's. Also, pretty much never have to build units. So you're free to boom while the war machine gets rolling.
I had absolutely no problem with the eki, sure you can't spam it all over, but there are plenty of places you can put at least 3. The gold on it after economics is great, the science from level 1 autocracy tenet is great, the culture is great, the food is less than a farm but why would you want food when you have a million cities and probably not exactly swimming in happiness?
In light of how powerful the capturing units bonus is, I'd say eki is just fine. If it was better it'd be a no brainer to chop down jungles/forest, as it is now you kinda have to weigh it a bit, the different yields, even worker time. And decisions is what makes the game fun.