I noticed how when upgrading logistics, it immediately phased out the usefulness of all of the units before it, even those of equivalent or even superior class.
I think we should be given the ability to combine 2 of the same units into one bigger unit of the current logistic capacity.
Heres what I think that we could do without affecting the balance:
2 units of X class units, 3 each. 1 is level 2, the other is level 4
Combined result:
take the average of the 2 levels, (if a decimal exists, add it to xp)
3+3=5 in this case, an extra unit contributes to the cost.