I agree that the Raven is a better car (like most things, if you want to see what's wrong with your car, look at the next model and the improvements). That said, it is a significant price delta. If you buy the 2018, you will be thrilled with what is a GREAT car. If you buy the Raven, you will be thrilled with what is a GREAT car. The difference is how much money you are going to spend. I bought a 2017 90D new and chose not to upgrade my order to a 100D when they came out. Some will say I have a crappier battery and the 100Ds are much better cars. In my mind I look at it like buying any piece of tech...when you buy, within six months there will be something newer out there, so you can't play the envy game for the newer item unless you are a "money is no object" kind of person. I am very happy with my 2017 and will likely keep it another 5+ years. Yes I could trade it in, spend another 30K out of pocket and get a new Raven (which is a better car) but the upgrades aren't worth 30K to me. I'm happy with what I have.
WRT your concerns about the 2 year old car with low mileage, it sounds like it is a November 2018 build which means it was likely delivered in December or January, so really we're talking about an 18 month old car. I am familiar with other show rooms which keep cars for long periods like that when it is a HUGE pain to move the car in and out. For example, the Tesla Gallery in Tysons Corner, Virginia is on the second floor of a shopping mall and not near any of the mall entrances. To swap out cars, they have to: (1) clear all the kiosks on the route to an exit, (2) remove all the doors and glass surround at the entrance, (3) bring in a crane, (4) pull the existing car out of the showroom to the elevated walkway, (5) crane it to the ground level, (6) crane the new car to the upper level, (7) pull the new car into the showroom, (8) get the crane and old car out of the mall, (9) reinstall all the doors/entranceway, (10) reinstall all the kiosks/signage. This is NOT a cheap endeavor and I could easily see leaving a car there for 18+ months. We are informed Tesla owners, but to a visitor at a mall show room, a Model S with MCU2 is effectively identical to the newest Model S on the street. Remember, the doors are open, the car is powered up, you can play with the touchscreen, but the car doesn't drive, suspension doesn't matter, etc.
Was it me, I would buy the 2018 car but you have to decide if the extra ~$10K is worth having the Raven or not. Either way, you will be happy with your car. Good luck and let us know what you decide!