My guy, you're stacking mods and expecting them to be balanced together.
SMS is a huge balance change for starters. You can get some real degenerate perk setups like the Paragon I got down to 0.02 Flux.
I am not using SMS together with this mod, i'm just stating that it is very difficult to balance the exponential curve with the use case. Especially when AI fleets profit from the system aswell. I was just testing how SMS and this mod would work together, but as i said the Regen on those AI fleets is crazy crazy and makes them nearly unkillable, with this mod alone, AI fleets can still become extremely strong. I guess excluding nexerelin would make it more balanced, but fighting a horde of AI fleets with extremely powerfull armor regeneration while your own setup is extremely expensive makes it very difficult to balance.
Also my intention is in no way to add it to every ship, like i said, when a single capital ship has an upkeep of easily 1M per month while frigattes are at 20-40k, you'd have to focus on smaller ships. My current game setup allows me to have an effective income of around 1.5 - 2M credits per month. With the current curve i can easily outfit all my Cruisers and Capitals with around 1M, but adding a single frigatte to it will blow it up to 1.3M. I wouldn't say that my proposal would make it easier in any way except you have very inflated income either way, because instead of stacking your already large ships, you'd have to focus on more smaller ships, it would just shift the weight towards smaller vessels while giving more control of the economy.
I am not in any way expecting you to add this feature, i just wanted to explain my reasoning. The mod is great, well made and as others have said, you can definetly make use of it. It would just be great to have an option that would allow it to balance the mod for different use cases and setups. I wasn't asking you to change how the curve works by default, just an option to make it static but still expensive.
Sorry if i sounded rude, english is not my main language.