I'd like to see an 'E/C' column added to the ship stats. It would contain the outcome of the following formula:
E/C = cost * (1 - ERes / 100)
Why? Because ERes is non-linear. If you want to make a ship 15% more resistant to EMP, you have to do something like 100 - (100 - eres) / 1.15, which is just a hassle. In addition, if you want to know how good a ship is against EMP, you have to involve cost anyway, so it's just useful to have.
Merlin/Munin owners: I'm so sorry about this.