Flame!! Flame!! Hahahaha!!

Sorry, couldn't resist! While I don't have any hard data on DCS performance or loading times on SSD vs HDD, I would still heartily recommend getting an SSD for your OS and other games. My preferred method is a separate 250GB SSD for OS and some programs like Photoshop and then a separate SSD for games. Most games improve loading times on an SSD but again, no hard proof for DCS specifically but it should benefit as well. There have been a few threads/posts mentioning SSDs eliminate micro-stutters but that has been quite a while ago and ED may or may not have broken any such functionality in the meantime. Even if it does nothing for DCS compared to a traditional 7200rpm HDD, an SSD will improve your boot times and will improve loading times on your other games.

Also remember that SSD performance degrades a bit the fuller it gets; most advise not to fill an SSD past 50-60% capacity.

I think one thing to consider is the price difference between SATA/m.2/NVMe SSDs. While there is a measurable difference between a SATA SSD an a NVMe SSD in terms of performance, you'll probably only shave off a few milliseconds on loading time and are therefore not worth the extra cost in terms of bang-for-your-buck, but still, if you have the cash, why not?