At 78 and after two tipovers of my 900 pound plus Honda Goldwing, I traded in the Wing for a new RT. Five years later, I have never regretted the decision for even a moment. At first I thought I would really miss the leaning, so I bought a little Royal Enfield 350 just to stay in the two wheel hobby, but after about a year I sold the Royal Enfield because it was virtually never being ridden. Whenever the weather was right for a ride, I went to the Spyder because I enjoy riding it so much.
I am a former MSF Instructor and in my opinion the Spyder is enormously safer than a two wheeler. Not only because of the inherent stability of three wheels, and especially the "reverse trike" arrangement of the wheels, but for the much larger frontal profile. The single biggest reason for car-motorcycle accidents is when a car/truck turns left in front of the motorcycle, with the driver invariably claiming to not have seen the motorcycle. The Spyder is much, much more visible to oncoming vehicles. In the five years that I have been riding my Spyder, I have not had a single incident of a vehicle turning left dangerously in front of me on the Spyder.
As to riding on gravel, I have had to do so on many occasions. I slow down and have avoided any major issues, although I did get a small piece of gravel embedded in the belt and had to replace the belt a month later. But the ride on gravel was stable and easy, unlike the "holy sh^^" feeling when I was on the Goldwing and the asphalt suddenly turned to gravel.
FWIW, my wife, who has been my passenger for most of the 60 years that we have been married, previously said that the Gold Wing was the most comfortable passenger ride she had ever had. But after being on my Spyder, she said that the Spyder was even better. And in my opinion, the windscreen on the Spyder outperforms ANY windscreen on any bike that I have ever owned.