I was interested as to why you felt the cost was OK, so I did some more rough calculations before i reached the point of building uranium processing in my own run. This time, going based on fruits/nuts to power ratio and comparing to the normal way of generating power on Gleba, rocket fuel in heating towers.
I will spare you the details, but as it turns out it is not as terrible as I thought. With Kovarex and a 2x2 reactor it is a bit under 3 times as good as rocket fuel, though it does require a lot more infrastructure. Without Kovarex, it is well under half as good as rocket fuel, so you would never want to use it for power before getting enough U235 to breed more. I suppose Nauvis just spoils us with easy nuclear, but increasing the efficiency to be worth it before getting Kovarex might be a good idea.
I write here mostly in the hope of helping you improve the mod, I set what values seem appropriate for myself. Even if you chose not to change anything, thank you at least for responding to my last post.