I think it would be nice if Rocket parts were 10 items of each ingredient in Expensive Mode+Space Age, and 50 Rocket parts per rocket, like in the base game

Also, T3 modules were changed to use 4 T2 modules in 2.0, whereas they used 5 in 1.1, and Rockets (ammo) needed Electronic circuits in 1.1, so maybe this could be reversed with Expensive Mode?

Nice idea.

Rockets are currently 1 of each ingredient, and 50 rocket parts per rocket, so your suggestion is a 10X increase.

In Expensive Mode, materials which are 'taxed' (such as electronic circuits or processing units) are not typically re-taxed later down the production chain, so this is somewhat counter to how expensive mode works. However, this would make for an elegant optional setting, so I plan to implement it.

Since the point of this mod is not to undo Wube's 1.1–2.0 changes but to reimplement a 1.1 feature, your second proposal seems out-of-scope and I think I will leave it for someone to implement elsewhere.