I would live aside your ideas of “building a system” as it is not the subject of this thread. This thread is about S2 driver and I would appreciate if you keep it this way. I do not sound very encouraging because I think what you do is very unfruitful. You can’t analyze the design of the drivers that you do not know and make assumption how minute design decision of the driver might affect sound. Come on, this is ridicules. Not one in the would tell you. What the point for you to learn how different $300 Chinese violin sound vs. some kind of famous Strud if you do not play the violin and do not even listen it.
Anyhow, let I give you advise what to do it you insist to extract an advice from me. Stop your crusade for ultimate MF driver. Bult some kind of bare bones playback installation on which you would like to use your MF driver. Begin to use that playback and begin to build reference points and practical sonic requirements for your ultimate MF driver. Than try a few existing MF drivers at your inhalation, including your 288 and S2 and define how far they are from the sound you need to be. You need a very specific definitions what they do and what they do not in context of your sonic objectives. Then, ONLY then you might begin to experiments to modify driver or build your own in order to accomplish whatever you are trying to accomplish.
Now read me very carefully: any another approach is a pile of shit that I would not accept seriously. If you long reader of this site then you have read this:
... and you shall know that I consider it absolutely mandatory and if people do not comply with it then I do not waste my time. Do not feel that I am too brutal to you as any other way to deal with audio is a waste of YOUR time. You might not understand it now but if you serious what you do then it will come to you.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche