I didn't feel a particular issue with the Super Helicopter mechanics. I expect they are different compared to the original games (all movement mechanics are slightly different in Redemption), but I must have adjusted quickly enough not to notice.
However, I can testify that Mr. Dark has bested me!

I started Mr. Dark's Dare with 60-something lives, then quickly got to 70-something just by repeatedly dying and replaying the first Dark Rayman level, collecting 2 lives for every 1 I lose.
Lost quite a few lives in the second Dark Rayman level (castle) before I figured out the puzzle progression. Dark Rayman levels are very challenging in this sense, because you must figured everything out on the run - you cannot stop and think, and have to be super-careful when backtracking.
I still had 60-something lives when got to the boss battle, and lost about 20 of them on the 6-stage chimera. Some of the patterns were harder to figure out, but most of the challenge came from the timing, especially the two Space Mama / Moskitos and Mr. Stone/Sax.
So I started the battle with Mr. Dark with 42 lives, went all the way down to 18, at which point I realized that I am nowhere close, as the most damage I could do to him was knock off 4 hitpoints (when he starts the flamethrower phase). So I chickened out and quit!
But here is the best part - I actually got all cages on the first playthrough, so... I can go back to Betilla and ask for another hitpoint, which is going to be a serious advantage in these extended boss fights. Now I am going to replay some of the levels (or all of them?) to regain the lost lives, and give it another try. I will not get to a Game Over!
