(The only easy one was in the "small difference" room, in which I didn't see any difference between the top and bottom half of the screen!)
It's there. The lower version is easy for me, while the upper version is much trickier. It's only a tile difference in the gravity line placement.
As was mentioned, it's possible to see the walls in the world where they're presumably supposed to be invisible. I assume you got it to work easily in your ASCII version. Too bad there's no way to do it in the editor, because I felt like I was missing out on a fun level.
You could have turned down your brightness.

In the ASCII version, the entire screen was invisible except for a small "flashlight" area around the player. It was really cool-looking. Of course, the two versions are mostly completely different as far as level design, with only a few similarities and shout-outs (e.g. the general ideas of levels 1, 3, 4, 5/6, 7, 8, and 10).
Some other rooms I liked:
Toad in the Hole - I like that you had to stay in the same column for a couple flips. I always enjoy sequences that make you move around in one area instead of just constantly pushing forward.
Heh, that was unintentional! You're "supposed" to jump into the first gap as the enemy is bearing down on you, then flip into the third gap, wait a bit, and flip to the exit.
My Lady's Chamber - I didn't see any logical way to get through this, so I just repeatedly jumped in blindly until I made it.
Right. The key is figuring out the correct timing. If you use one of the enemies as a guide of when to fall, it's easy as heck. Other than that, it is just blind trial and error.

I just have one question about something I didn't understand... Why do you hate Sony?
Because their consoles suck. Just kidding. In the game, it's actually a bit of an easter egg: look closely at this room and the rooms around it, especially the enemies, and you might get the reference.