Okay, I fixed it. Reactors that produced 1mil e/s produce a tiny bit more than that with this, and the softcap is now 2 million as intended. I'm posting this in every thread where people are concerned about power generation.
With the PowerGrowth value halved, my 1mil e/s reactors still produced 1.4mil e/s rather than 1.05mil. The setting I chose gives the reactor I'm using for testing a power regen value of 1.2mil e/s.
Code:
<PowerCeiling>2000000.0</PowerCeiling>
<PowerGrowth>1.000278</PowerGrowth> <!-- 1.000696 normal, 1.000348 halved, 1.000278 2/5ths-->
The halved value is the safest for small ships - the value I chose is only valid if you're using 1mil e/s and 2mil e/s reactors as the goal post.
I'm thinking 1.000348 may be ideal.