Dear Grumpy, the answer is absoeffin'lutely YES.

To show you how much "yes", I made an experiment especially for you, since I've got two DCS installs, both updated to today's OB spec, one on my good old 7200rpm SATA HDD, and one on budget-class SSD, with budget-level read&write times. The experiment was as follows:
a) system reboot;
b) launch the DCS from desktop shortcut;
c) when it loads navigate to Nevada Instant cold start mission for the Spitfire (I chose Nevada for its highest RAM demand) and load it;
d) measure the total time required between hitting the DCS shortcut and getting into the cockpit, ready to hit "fly" button, using stopwatch.

Result on HDD - 9 minutes 39 seconds;
Result on budget SSD - 1 minute 35 seconds.

Let that sink in biggrin.

Granted, both loadings required the game to rebuild terrain metashader files, which I purged before, so they were somewhat longer than usual, but even with metashaders ready the relative difference would be the same anyway.

Not to mention great reduction of disc-read-related stutters during the flight, as DCS is programmed to load scenery assets all the time. Purchasing this poor-man's brand SSD was the second most successful investment (after the gfx card) I made for this sim.