[Rollo]

Geo - what you mean is the effect when you half the size of supply storage as well as the supplies they carry. When engines carry more supplies than the storages, the AI will use extra illegal engines when the design calls for 'supply storage' ability.

re: changing supply storage - I do not agree with that.
Firstly changing the size of the storage can have unintended foul effects with the AI (I am talking custom AI here).
Secondly I think that the reality reason is a bad one. Neither of us is a spaceship engineer and knows how engines store their supplies and how supply storage works. There can be many points and explanations made this way or other. All of them totally hypothetic and moot. I will not go into such a discussion.
Thirdly, arbitrarily rasing the values for supply storage (as well as allowing them to count as cargo on transport hulls) will have profound effects on the game. The range of fleets will be raised and overall play balance effected. I am not aware of a balance issue that said: 'Fleets donn't have enough range.'

For these reasons I think it is better the leave supply storage alone.

Rollo