I got the Premium a few weeks ago because I got sick of all the CTDs with the PMDG 737. First time I had to use it, it worked like a charm. I restarted the sim, started at my departure gate, and once in the cockpit at the gate, I loaded the flight from Volanta auto save and it put me in that save position and the FMC had all my flight still programmed in. I continued on to land and when the Volanta flight was complete it recognized the total flight time and distance just fine.
However, I had a CTD with the Salty 747 yesterday on final and when I tried to reload an auto save flight from 8,000 feet the FMC was empty with no flight plan and I had to fly and land visually with the aid of my flight route in Navigraph Charts.
So I guess it works with some planes pretty well and not so good with the rest. I haven’t tried it with any other planes yet. I mainly have CTDs with the PMDG (at least 1 or 2 in 10 flights) so if it saves complete aircraft state and flight plan it is worth it for me for $40USD per year.