C rated core modules tend to be avoided as they are a bit in between.
.......
Good post, and I would add that all classes also have varying power draw. Cost, mass and performance are all important factors, but often times it's the lower power draw of some that dovetails or synergizes with my builds, allowing extravagance in areas I might have to be more mindful of otherwise. And of course lower power is lower heat. Mixing in some Ds (sensors and life support among the cores on my boats) means lower cost, lower mass, higher jump, lower draw and cooler temps.
And OP, I totally get the goal of a Sol permit. It was my first real definable goal in Elite. Good hunting commander.