I think the main lesson learned about 7 seat versus 6 seat is to go see it in person if you can. I was firmly in the 7 seater camp until this morning.
I agree. I would even encourage seeing as many different Model Xs as you can manage. I have seen several Xs now, and the seats behaved a bit differently in each of them:
(1) The showroom 7 seater 2nd row left side seat would not go all the way back (an engineer came out to work on it while we were in the showroom, it seemed if he put enough pressure on it, it would then go all the way back)
(2) The showroom 6 seater 2nd row right side seat would go full forward or full back with just a tap on the control on the back of the seat (no other car did this, even the right side 2nd row seat in that car). We had some concern about getting crushed while in this mode, and an engineer came out to say that it would not work if there was more than 40lbs detected by the seat sensor, but there was no resistance sensor. However, the motor is weak enough it would burn out rather than crushing a limb.
(3) The test drive 6 seater would not let the car drive until the driver adjusted the 2nd row seats back, squashing the people in the 3rd row. (Apparently this has to do with moving the seat with one control [moving to enter/exit] vs a different control [moving to adjust fit], and the Tesla rep said once he squashed the people in the back, that they could use the other control to give themselves some more room, but this seems a poor experience)
Overall, the seats seemed a bit 'beta' and you may want to wait a bit to see what issues persist and which are solved by software updates.