They will dominate the early and midround easy if you do nothing. Being a competitor to dwarves you should make the defense a little more expensive.
And population bonus also affect the Dragons DM production. So it is mainly the GC bonus that is the issue for efficiency later.
Dwarves can invest more per building than Dragons can with their workers btw.
also if you DO want to compare humans with dragon.. that knight is 7 points per unit that dragon is around 10 points per unit. Those extra nearly 50% offense bonus makes the 210 gold per point way to cheap. Should be around 235 gold per point or even 240 and that is still cheap as you require less units per dragon military in the form of upkeep the greater your population bonus gets. 30% pop bonus makes it around 12,2 points per unit for offense.
I think you misunderstood my post. It's the Black Dragon that costs around 240 gold per point offense. It's the human Knight that is 210 gold per point offense.
About the 10 point offense vs the 7 point offense in terms of space-efficiency :
Ofcourse 10 point offense is more space-efficient than a 7 point offense unit. But at a price difference of 30 gold per point, it will mean that Dragons won't be able to train the same amount of units for the same income. They will eventually earn it back due to their space-efficiency. But let us take a look at how long that takes.
70 points offense from 7-point attackers at 210 g/off costs 14.7k gold and takes 10 spots.
70 point offense from 10-point attackers at 240 g/off costs 16.8k gold and takes 7 spots.
So the difference is 2.1k gold for 3 spots that might be used for workers.
So 1 worker will need to earn back 700 gold.
if you take 0.5 diamonds = 5 gold (which is the case at 30% housing and 40% banking), it will take 140 hours before the price-difference is earned back.
As a rule of thumb for a 5-week-round, is that it should not take more than 5-6 days for an unit to earn itself back. If it doesn't do that, the player won't be able to keep up with the rest of the players. So that bad ain't the 240g per point offense for the Black Dragon.
The defensive elite of the Dragons is less space-efficient than the defensive elite of the Humans, but costs more per point of defense (at 30% housing and 40% banking). So even if the offensive elite might have been too cheap, I'd say the Dragons are penalized enough through their defensive elite.
Also it's not my aim to make the Dragons totally the counterpart of Dwarves ; it's just an observation from me as creator about the race. With balancing, I try to balance them with Humans, as they are considered the default race.
I'm currently thinking about raising the price of Hydras a little bit, but decreasing the price of the specs, to give people more the incentive to train them at OOP instead of elites. from the start.
Also thinking about changing the spell to something that just trades a certain percentage of diamonds for gold. That way the spell won't be that fatal in regards of upkeeps that suddenly might not be paid anymore.