Played through your latest version that was in the Level Testing thread.
I would put a ceiling generator in this level on screens D and F. Persistent players (or ones with a cape, especially if an earlier level provides one) can make the jump to (or over) the pipe and skip over 3/5 of the entire level.
The sprite you would be looking for is Custom Sprite D0.
Like so.
However, this particular jump would cause a new problem, since Mario will most likely go over the screen, the generator will make him bonk his head, having him run the risk of landing right in front of Chuck, ergo, a cheap hit. Possible solution? Lower Chuck's platform a tile or two.
This isn't something major, but the change in music seems off here. Of course, it's mostly just me thinking the canopy section's music can cover the level as a whole and not just... the canopy section. Again, nothing that "needs" to be changed at all.
The placement of the checkpoint here is slightly annoying. Perhaps put it on the higher ledge altogether?
Be sure to replace this sphere with Custom Sprite 02.
I do not feel this Star 2 Block is necessary. If the player is too slow with making it to and across the muncher field protecting the keyhole, then they do not deserve a damage-free second chance. Your Star run allows plenty of time to make it through in the first try. If you still want to put a block here, then I suggest the 1up Bonus block (and since the player will have most likely collected 30 coins already in the level, then it's just a free life).
Also you should run through your level a couple times since a major gameplay element was added to the latest base ROM. (Mario powers down like in SMB3), so be sure to readjust your difficulty balance accordingly.
Other than all of that, very, very smooth sailing. I still stand by what I said before in that your level is just about good to go and should pass the last stage in level testing, which is a major plus in my book.