Absolutely gorgeous spec Seth, really well thought-out. It is such a personal and subjective decision when selling a car like this.
I will be the anomaly here and if it were me, I would sell it. Your post strikes me as more in love with the idea of the car than the car itself. I can appreciate this is as a fellow serious auto enthusiast and also an ex-aventador owner. Mine was several years older than yours, was an absolute nightmare around the track, reliability issues and lacked that analog feel that older cars provide. I think the latter there is where I decided to sell, as much as I did enjoy the car, it never ever even came close to the analog feel of ripping through a gated analog italian car. Bought my diablo roadster and never looked back, it requires every ounce of your attention and has that pure analog feel that I thought the Aventador lacked. Have not missed the AV a single day, my bigger auto regret was selling the Murci SV before prices exploded but sold early as the egear was horrendous. To me, it was more important about the interaction with the car, flying down back roads and that engaging analog experience.
Back to my original point, it really depends on what is important to YOU. Regarding investment, I don't think the Ultimae will command the future premiums the SV and SVJ will. This is evident by the 50th anniversary edition for the aventador which is not fetching near as much as a premium. Or more akin to the murci last edition which is not as sky high as you would presume.
All comes back to personal preference but I would sell it, consolidate funds and put towards a F40. Which IMO would be more fun to drive and certainly a better long term investment. Really think it comes down to what you want from the car?
From back in the day:
