0. Of course it's subjective - most everything is. I favor a minimalist design (I'm from Germany, s fan of Bauhaus and my wife is a retired high-end interior designer - that's why. The S is much, much, too cluttered with many too many buttons, stalks and knobs .
1. Right, I agree the 3 is a better handling car. That was *my* point. However, it's not only because it's smaller (by the way, smaller does not always handle better than larger), but also the stiffness of the suspension, steering etc
And this handling is evident in normal day to day driving. I only metion Track Mode in response to the comment that the S is quicker/faster.
If one truly enjoys the experience of driving, the 3 will truly inspire you (especially the. AWD). You don't even need the Performance version for that. Many Americans mistake "speed" (especially 0-60) as the indicator of a "performance", when it's more about weight distribution, steering response, suspension etc. (In fact, I always keep the steering setting in Sport, even in long trips).
That's why s low-end Porsche 911 performs "better" than the highest end Mercedes S Class.
The S is like a Mercedes S Class and the 3 is like a Porsche. To your point, it's subjective - it depends what want. I like performance so for me.the 3 is an upgrade.
2. ??? You're making my point for me. Ludicrous is a software upgrade, not hardware. It stresses the hardware more, but enabling it is purely software. Anyway, you are correct that it involves more than the battery but also the motors, hence making my point for me... In the 3 both the motors and batteries are upgraded versions compared to the S.
So, if Tesla allows a ludicrous mode for the 3P it will be quicker than the SP100D, because of superior handling, batteries and motors, and lighter weight. However, 1) Tesla may not want to cannibalize their sales so that may not happen. 2) to be fair, when the S refresh happens this year, everything will change.
Anyway, most decisions we all make are based upon personal preferences (except the performance handling - that's objective), but that's what the OP posted about; the difference between the two.
My view is that the 3 is an upgrade from the S. It's like coming from a Cadillac to a BMW M3.