JB - I understand "second guessing" your SR+ decision - we all do it. All I can tell you is my experience. I'm a "caraholic", having owned literally dozens of cars over 50+ years of driving, as well as well over a dozen motorcycles. In that grouping of machines I've had everything from an AMC Gremlin to high end sports cars. And I pretty much second guessed each of them. Advertising is a powerful force, always making you want something new. That feeling is stoked by the many car magazines and websites also pushing the "newest and greatest".
In the end the reality of owning these machines is very different. They all depreciate, have "issues", cost more to maintain than you expect, and eventually we lose interest or move to something else. And the reason is that the hype of sports cars is very different from reality. Most state speed limits rarely exceed 80 MPH, and most cities have 35-45 MPH speed limits within the city. Add to that traffic, congestion, parking lots and other normal situations, and the ability to use a high performance sports car is very limited.
Historically, there has been a large difference in the way car manufacturers built their machines, and consumers made their choice. If you bought an "American Muscle" car, you wanted high torque engines at lower RPMs, giving a feeling of power from a dead stop. "European" engines produce less low end torque, but higher peak HP. That's great for high speed driving, and since many European roads don't have a speed limit, driving at 125MPH is not uncommon at all. For a long time that was the choice - high peak HP or low end Torque. No wonder people had "buyer's remorse". If your perspective changed - from driving experience, advertising or anything else - you had the wrong tool for the type of driving you wanted to enjoy, and so you switched cars.
That's where EVs have changed everything. The torque on an EV motor is instantaneous, making for a VERY enjoyable driving experience. So far the automotive press hasn't explained this change very well. My Mustang GT manual transmission car was very enjoyable to drive - because I was actively engaged in driving - shifting gears, hearing the aural cues of the engine revving, and seeing tires smoke if I wanted them to. But if the goal was quick response and instant acceleration the EV drivetrain on the Tesla actually accelerates faster than the Mustang from 20-50, 30-5-, 30-70 and most other speeds. It's a constant thrust without having to change gears. EVs are truly unique driving experiences.
I'm pretty sure that if you take your SR+ and put it in context of Carlsbad CA roads, allowing for traffic, speed limits and all the rest, you'll be amazed that you won't have any buyer's remorse. The car will just do everything you want it to do with little fuss. Can a M3P accelerate quicker? Sure, but how much quicker, and how often will you be able to use that power? I also prefer RWD cars. I don't like the extra weight on the front axle, and find the steering feel is far better. That's one thing that the European cars get very right - any Porsche will have good steering feel, and needless to say the Ferrari excelled in that area. Today most cars have abandoned traditional steering racks for electronic steering - it's a different feel.
My point? Simply this, there are so many limitations to how/where you can enjoy true sports car driving that cloud our judgments to what we may want versus what we can expect the reality of daily driving to provide. And that difference leads to "buyers remorse". Don't worry about it, just realize it exists. If you find that the SR+ doesn't paste a smile on your face every time you drive it, that doesn't mean it's a bad car. It just means that the driving you're doing at the time is a bit of a mismatch for what you expected. The analogy is a toolbox - sometimes you need a hammer, and if you do a screwdriver just won't be a good substitute.
Buy the car that matches most of your driving needs on a daily driver basis. You can always rent another car for those mismatch times. You have a Tesla SuperCharger right in your backyard - the SR+ range shouldn't be an issue at all. The car will likely be the best tool for 90%+ of your driving needs. Think of how often you'll have a chance to floor a M3P in your typical driving day - my guess is that it won't be that often. On the other hand, you'll be able to floor your SR+ from 20-50 just about every time you want to. In those situations, how much better would a M3P+ actually be? You won't be accelerating to 60 or 100, but likely only 40-50. And with no front motor when you do enjoy a long sweeping turn in your car, the SR+ will likley have better steering feel - your power will be from the rear drive wheels, not from a front engine pulling you through the turn. The M3P will ALWAYS have AWD steering feel - the SR+ will ALWAYS feel like RWD. I know which feel I prefer, and that is why I still have a RWD Tesla and will likely keep it that way.
To me the compromise isn’t 0-60 acceleration times, it’s having to live with the feel of AWD all the time. I’ll gladly give up some acceleration that I’ll use very rarely to enjoy the feel of the car every second I’m behind the wheel - and that’s why I tell all my friends to buy the SR+.
Rent a SR+ and drive it like you would if you owned it - I doubt you’ll find it disappointing.