Hi there Livelyjon!
I hope I can be of some assistance to you, but from what I've heard from some users who've put this to the test, it's generally the same whether you use an SSD or HDD with X-Plane 11.
One person that put this particular aspect to the test, found almost identical if not identical load times for X-Plane 11 on a SSD and a HDD, and worked either way. The game fully loads and works on both, but I'm not to sure wether this affects gameplay and graphics performance; but i'd assume not.
Hope this helped!