By compatability, I mean how one person's code doesn't work with another's. Not that they should ALL work together. I think, however, the last time I used the pixel movement code for the PI test, it was still being worked on were it would allow other code compatibilty. That's why I should check up on it. The pixel movement source was HUGE, and had a lot of stuff (heck, most of the game's special features run on that one source). So if it's been upgraded, I might be able to find and throw in a sprite de-limiter. Of course, I need many other things like overworld enemies that chase you (pixel movement), respawning of enemies (because as of now, once you kill them, they're gone for good, which doesn't make for a good leveling up system), icy ground, dangerous ground, etc. And while I've seen things for each of them, I can't throw them in hodge-podge and expect it to work (too much conflictions).
Otherwise, without compatibility, you sort of have to code all the features of your particular game yourself, because then you know everything works with your system.
As for what you're doing, I guess it comes down to what's easier for you. Don't work yourself over if things don't seem to work out just right. I admit I'm concerned about the problems that'll come down the line, though, by messing with just the walking alone.