Oh, one other change to Meta Knight from Kirby that's most noticeable in Milky Way Wishes (with the water planet): He doesn't inflate to fly, so he doesn't get super buoyant if he goes into the water while already flying. That's always a little mechanic I loved doing with Kirby, so, it's noticeable. For me, at least.
(Same with areas with up-wind.)
It sure was tricky to get to that cannon quickly. If only you had some power that would allow you to go faster.
I'm fine with fighting Heavy Lobster a lot, because Ultra gave him an awesome song.
...oh, and you mention the lack of puffing later on. Man, I just cannot catch a break.
I mean, I see the Great Dragon as orange, rather than brown, but to each their own.
And here we have the only other theme in this game that defies the Masked Dedede theme being uncontested champion.
And, yeah, he was super tough for child!Data.
Note that that "Fly! Meta Knight" apparently occasionally replaces the opening when you start the game after you've beaten this mode.
I think Helper to Hero is considered harder because of all the Helpers. And some are really tough - like Wheel (despite the invincibility), or Parasol.