You make valid points, but we are talking a difference of 74-77k versus 75-80k. For those who are stretching to buy the Model X base, save up $77k + appropriate taxes plus $1200 delivery fee.
According to this
mega-thread: 762 HP (259hp F + 503hp R)
the p85D has 188hp F and 470hp R.
the p85 is 416 hp
the S 85 is 362 hp (and the S 60 can only get 302 hp out of it due to the inverter). This is now being listed as 382 hp for the motor only.
According to this
spec page, the motor horsepower is identical. I stand corrected, but I blame Tesla Motors for introducing confusion about overall horsepower.
I'm really, really glad hp means so little to me. If I were shopping with priority emphasis on that attribute, I'd go nuts. I'm only remotely glad I understand what the iconel contactors are, due in part to following SpaceX.
I am in full agreement that the motors now (as well as the batteries) are the same components. I read a quote that the Model X and Model S share 30% of the same components.
Broad strokes:
chassis: no
body panels: no
wheels & tires: no
glass: no
latches and door assemblies: mixed
door handles: no
seats, interior paneling, headliner, vents, carpeting: no
fans, service motors, lights, cabling: yes
displays: yes
steering wheel and controls: yes (?)
Power systems, motor, batteries: yes
Sensors, sound system, internet: yes
Software: majority
In brief, I think the difficult/complicated stuff they can share is being shared. Since they make their own plastic and aluminium parts I think and a price differential for all that will be by the pound, which is negligible, since aluminum coil is priced at between $2000 and $4000 a ton (versus $500-$800 a ton for galvanized steel) and a 10% difference in mass won't be more than a couple hundred dollars. My guess is that the windshield to the heavens is a greater contributor to price than the stamped aluminum mass differential.