Darm is rightly the toughest in the game. Even with game speed set to SLOW, a high level, Lair's ring, and Barrier magic, you will still only win by the skin of your teeth. Those orbs are so hard to dodge.
I achieved one of Super Darius II's many moving endings. What a matter. Hey, it's a 1CC though!
I will play more of the game explore more levels/routes/bosses, but my initial impressions are problematic. Graphics are nice, but sprites are too big. You run the risk of accidentally colliding with an off-screen enemy approaching from above or below. Sprite flicker can turn boss attacks invisible - high-speed bullets + invisibility is a lethal combo. If you can manage to not die from these programming/design oversights, the game is easy. If not, well, you are in for an incredibly frustrating time. In these respects I enjoyed the MegaDrive port more, since the game was balanced around an enclosed 4:3 aspect ratio.
Super Darius I doesn't suffer from these problems, because the sprites and play-field are much smaller and are accommodating to a single screen.
Also, T's Music is worthy of a great deal of praise, and I dig the remixed soundtrack for Super Darius II. However, it just doesn't compare to the memorable strangeness of the arcade original (the Boss 2 track and Say Papa suffer the most). It's a little too "poppy" and "fluffy" if that makes sense. Maybe "indulgent." It's nice listening but I just wanted to voice my absolutely-true-opinions.