As a new S85D owner, I can certainly add a little here, though, if you read this thread carefully I am really not adding much new to this thread; it has been a great discussion.
I wondered and felt remorse when the 70D came out. Maybe I should have gotten it (not really a choice, I had my car).
I would have save $10k (I told myself).
I don't need to go that extra 30 miles.
For many, the 70D is the very best choice, and I am really glad it is offered. Go Tesla!
And the other issues that have come up here are important, more so for some, less so for others.
It makes no difference day to day, 70D to 85D, best I can figure.
But there is more. Range is crucial when you need it (or you have to plan better and have more time).
My older brother, a long time EV driver, convinced me to get the 85 over the 60--always get more battery he said. His experience is with an EV that goes 36 miles. He is the expert in many ways. (He now also has a Model S 85.)
My wife and I take a trip to KC a few times a year. We have (only very recently) a SuperCharger (SupC) at each end, and we used them both at least twice on the first M85S trip. With 199 miles between SupCs, which is not to be the norm (they will be closer), I had issues. I was a novice, and that is important. I was used to driving an ICE, going fast, 5 mph over the limit (80). I filled with energy at the Council Bluffs SupC, and took off for KC. I had to slow down after a bit, then slow down again. I started to worry if I could make it, looking at how far Nav said it was to my son's vs projected range. I got to my son's home with 31 miles left, and 21 miles to the SupC (Independence). Without an 85kW battery, I would not have made it and would have had to make different plans. My speed at the start of the trip and the hills going into KC made the difference, I believe.
Then on the way home, I filled at Independence and headed for Council Bluffs. I did not drive so fast (I think I started at 70 mph) but soon had to slow, with the Modes S warning us about a lack of power. There were very strong headwinds. So going back the 199 mi I had to get 45 min worth of energy (that is it's own whole story, with a red herring power stop) at a J1772 in NE City.
Sooooo, I need an 85. Maybe there will be a SupC between the two in the future (I think there used to be one on the Tesla map, but there is not one anymore since they revised it).
Could we make that trip with a 70? Absolutely. Would we have to plan better, allow more time, make sure of plugshare spots that work, drive slightly slower? Absolutely (IMHO).
Do I wish I could have saved $10k? Yes.
Am I glad I have more battery? Yes.
Does Tesla change its offerings at a pace faster than I ever imagined? Yes.
If you don't need to spend the money and don't want to, don't.
Realize, and if you have not driven an EV you won't completely get this until you do, that EPA range is not what you use to drive if you have any distance in your day/trip. You use projected miles, almost always less than the rated range miles. So when we are talking 240 vs 270, that is ideal (and may actually happen now and then--if that head wind had been a tail wind, I felt like I could have gone to Canada without charging).
In my experience, and I haven't done a winter yet (which will reduce milage in the MS, just like it does with ICEs), if heading away from home, I count on 200 miles not 270 with an 85, and make sure you understand backups and time issues with EVs.
Ten years from now this will be different. We are the future and early adopters driving Teslas.
So be careful and thoughtful. Either way it is a great car. I'm betting the 85 will be replace within a year, just as the 60 was. My 2 cents.