The sample of this benchmark is poor; I logged in just 3 times. Each time I logged into Wayrest, next to stables, using my main Tank build.
So load times from boot-up beep sound to character being visible in Wayrest:
Sandisk Extreme Pro 960 GB.
SSD: 2 minutes, 1 second.
HGST 1TB HDD (PS4 Pro default)
HHD: 2 minutes, 25 seconds
Take a loot at the attached PNG for extra information, such as how long was spent time in different phases.
In conclusion, you should save around 20% in loading times if you have an SSD drive. Not a massive difference, but difference anyways. Also the map seems to load a bit quicker all the time, including all the icons in it, but this can be just because I believe it to.
And no, I didn't spend 300 pounds to get a Sandisk SSD. This is a spare one used for testing.