Round table

I always choose Gunisson as the starting hero for the Castle. We can estimate how much stronger, for example, Craig at level 10 is compared to Gurney.
Damage increase for Craig with experience: 1+0.3*(1+0.05*10)=1.45 times
Damage increase for Gurney with experience: 1+0.3=1.3 times
1.45/1.3=1.115.
Conclusion: Craig's damage (level 10) is 11.5% higher than Gurney's.
But the ballista is very helpful for defeating neutral creatures.

And what should be taken from this math? I, for example, see that Craig, with 9 movement points, after visiting a couple of attack upgrade locations or with the worst attack artifact, almost guaranteed eliminates an entire stack in minimal turns, while Gurney will almost always have a couple of griffins left, which will retaliate and then full stacks will attack them.
P.S. Don't take my example as an indication of how to play the game. I was given an example of a simple calculation, and I gave an example of what might be behind these percentages.