I just posted something regarding the P90D versus P85D, Ludicrous versus Insane on Tesla's other site. While not certain, based on Tesla saying that a P85D upgraded to Ludicrous will not be as quick as P90D with Ludicrous. My P90D without Ludicrous appears to be quicker than a P85D (2.97 versus 3.2 0-60). Point being, for $3,000 instead of $30,000 you might consider upgrading to a 90D. If the same holds true, the 90 kWh puts out a little power, its possible that the 4.2 0-60 for the 85D might improve by a couple of tenths. Again, just possible.
As far as seat of your pants, probably won't fee much of a difference. If anything, you might feel the 85D or 90D is a little quicker since with All Wheel Drive, it will have better traction and launch out of the hole quicker. Just might not carry the same speed all the way to 60 MPH with less horsepower. But your butt feels torque more than it feels horsepower, so it's likely the 85D or 90D would "feel" quicker to you, despite taking an additional couple of tenths to get there. And for the $3,000, you might get it to where it's almost identical. Worst case scenario would be that it's the same speed, but you've added 6% range.
That was another test I did. I had read where most were showing only a 4% gain in rated range from a 90D versus an 85D. Tesla states "about" 6%. However, on my P90D, I did my first full range charge to 100% and it gave me 269 miles of rated range, versus a P85D being rated at 253. So I got a 6.3% increase in range on my car. 90D, if the same, would increase from 270 to 286/287 rated range.