Well, since the game was sort of designed to be a hopped up NES looking game, it's a little unfair to make it seem as if the NES couldn't handle this kind of game. I'm also not sure why an NES version would need "better graphics and music" since it's a clear homage to NES gaming and would need basically what is presented, with some technical cutbacks due to real NESing.
It's not that it needs to have better graphics and music, it's just that if they actually made an NES version (without putting a whole new console inside of the cartridge) the game would most likely be watered down so hard that it wouldn't even be worth bothering with... It's not just the lack of parallax that's the issue, it's that the game uses pretty much all the colours in the NES palette and then some all at once with no regard for palette limitations either in the sprites or in the BG tiles, and then there's the music, okay they might be able to put a VRC6 in the cartridge, so the music COULD end up untouched, but it would add sound-clipping (not like that bothers you)... But in case they ended up unable to use the VRC6, which is a possibility, then the entire soundtrack would have to be redone with just the 2A03, so there goes the 3 best channels and a whole bunch of musical detail, not to mention, the sound-clipping would get worse with just the 2A03...
The gameplay would probably be fine, but the flickering in that game would be other-worldly (unless the sprites were made smaller or at least less wide) they'd have to either cut out some enemies for being too big, or put them on the BG layer and figure out if they can even animate or move them depending on level design, and if they went that route, level design would have to be changed in various spots, oh and, say goodbye to any hint of smooth animation, especially on the enemies...
Pretty much every boss except for Tinker Knight and maybe Plague Knight and King Knight would have to be re-designed, or they'd flicker so much that the fight would be near impossible to see...
I'll admit that a real NES version wouldn't be unplayable, but I know I'd rather have it on a system that can actually do the game justice, unlike the NES...
That's why I said re-interpreting the soundtrack would be a better idea...
I'm not sure of your point. You would have to do this regardless, and I am saying it's OK to have a soundtrack where sound effects will stop a song channel during the duration of the sound effect.
PCE would pummel the soundtrack if it were a CD release. It'd be funny.
The game unfortunately uses typical euro-esque chiptune stuff with a hint of Capcom percussion, so I got tired of the soundtrack rather fast.
It sounded a little uninspired, I guess.
I'm not saying it's not okay to have sound-clipping, what I mean is that a PCE version of the soundtrack should sound more like a PCE soundtrack, and not like NES on-steroids but missing details, also I'd like it a lot better if it turned out A LOT less Capcom-esque...
Putting the soundtrack on CD would be the easiest route, but c'mon what's the fun in having a CD play NES music on-steroids? If the game used the CD for the music, I'd vouch for the soundtrack to be re-created with the YM2151, then just record that and put it on the CD, now THAT would be a good version of the soundtrack!
(I know I wouldn't do it though because I suck at FM and I'm not enough of a fan of the soundtrack or talented enough to attempt to cover it, also it's too different from my style)