I know this is off topic, but no. . . just no. Space Marines throw the equivalent of snow balls compared to the vast majority of Sci-Fi, let alone military Sci-Fi.
The space marine's base most firearm is essentially a miniature, rapid fire rocket launcher, which are pea shooters compared to their heavier gear. Just off the top of my head and from what I know of each series, Star Wars, Mass Effect, Unreal, Xenogears, Xenosaga, Fallout, Star Trek, Universe at War, Borderlands, Bioshock, Brute Force, Doom, Dead Space, Jak, Lost Planet, Metroid, Star Ocean, Quake, Prey, Starcraft, Halo, MST3k (the funny ones still count!), and Spore can't consistently compare to WH40K versatility, quantity, or raw firepower. There are certainly more powerful Sci-Fi universes out there, but to say the vast majority of them are is silliness and obvious hyperbole.
On topic, I say it comes down to numbers and the scope of the battle. If you were to pit the space marines against the full might of the eldar in their glory days, they'd undoubtedly lose. The same applies for the DAoT, as far as I see things.