Yeah, went ahead and did config today too and will definitely wait for the 400 mile pack. 300 will likely be close to 300 miles. Range in King on EVs.
From my 7 years+ of having Teslas, people have to realize it is likely for some:
1) You start with 300 miles at 100%, but it usually isn't good to be at 100% long. Thus say 90% is normal like Tesla so you usually have about 270 miles to start.
2) You will likely lose a good 3-5% over time from the starting range, thus subtract 15 miles long-term from that 270, and you have 255.
3) Drive over say 55 miles per hour and that is with the superior efficiency of a aerodynamic Tesla and you loose a good 10% or so, end up at 235. Even here the charging network range becomes key.
Then on top of that; cold climate/rain/snow/very cold, subtract a good 25% - and you have about 178 miles usable. Or towing something heavy, subtract a good 30 (at minimum), and end up with a measly 165 in good weather flat ground, etc, and in cold weather towing, a measly 125 miles or so of range.
This is why the 400 mile pack is so key.
-T