Not necessarily, you could do the whole thing in one project using the IF color mode enabled statement to send the player to GBC only vs GB only scenes. its an interesting idea actually. Never thought of that until you prompted it.
Had a look on the speed issue and it seems its because the DMG has a slower CPU causing hard slowdowns. You also have slowdowns on the GBC when there five or more enemies on screen. It can be done without slowdowns but not in GB Studio. Nice artwork and game!
I liked this a lot but had the same issues on the DMG via the non-demo file on your main site. Also the palette would sometimes just go all black on the characters at times. Really great start but needs some tweaks. Would love if it worked on both GB models as I would be playing on DMG.
