I'm in MA with AWD (Performance Stealth). I'd buy an AWD if I was buying today.
I can't tell you how many posts have been on these forums by new buyers and they buy a cheaped out base model and then realize this is such an amazing car and realize they really screwed up and should have went all in for LR, AWD or Performance. They realize this is a long term deal that they are all in and why on earth did they buy the cheapest model.
I got the MA rebate on AWD Performance, so I'm not sure what OP is talking about.
I drive in MA and NH. No question, I want AWD. OP has the right idea get Aero's for winter snow tires (regardless of AWD or RWD).
Keep in mind at 240 range you normally don't access the whole battery. Sure, on a long road trip you can charge to 90-100% and run it down to 10-20%, but you don't do that daily, typically. On a daily basis (opinions vary a lot on this) but I would want to run say no more than 30% to 80% on a daily basis. That's only 50% !! Let's be more conservative, say 20-90% (daily, that's a lot for every day). 70% of 240 is only 168 miles range. Now factor in Heat in winter and take say about 30% (that would be on a fairly cold day which doesn't happen every day but you can get a 2 week stretch around 0F in MA). So that leaves us 70% of 168 is 117 miles.
78-80 mph is pretty fast for MA. I hear lot of people say "everyone drives that fast". I don't think they do. I typically drive 65 mph and people are not zipping past me. Some certainly are but I'm passing plenty even at 65 mph. A lot of roads in MA are 55 MPH. You will take a good hit going 80 mph in a Tesla. Probably cost you 20 wh/mi (~8% hit). So now lets apply 92% of 117 is 107 miles.
So during a cold spell in MA doing 80 MPH and running the battery down 20% and charging to 90% you get ~107 miles.
What it boils down to is more range is more convenience. During the cold spells you might want to stop at super chargers or slow down.
Even running car down to 20% when it's 0F out and your stuck in traffic with the heat going is to risky for me.
Get the damn long range !!
AWD includes base AP, Premium interior and 310 miles range. You can get by with RWD in MA, but it's just a matter of how severe a conditions do you want to drive in to get from point a to point b. Also if you have a back up AWD car that might sway your choice (I do, but I still got AWD because of conditions in NH, I want at least one car in the household to be AWD). AWD is similar to more range, It's convenience, don't have to plan around the weather as much as I would with RWD. It's snows badly I work from home. But if your job is really demanding like a heart transplant Dr, maybe you want that AWD. I want me EV to impact my driving habits as little as possible.