TBH, I don't use my New 3DS XL for GBA games for the exact advantages you listed by using a mGBA core emulator, plus the screen resolution/scaling just doesn't look right IMHO on the 3DS for GBA games. Here is a photo comparing the game start screen on my 3DS and on my RGB30: https://imgur.com/fA8EQP7 The 3DS screen doesn't look as bad as the photo shows, but it is nowhere as nice as on the RGB30's screen. I'm using the mGBA-rumble core on various handheld emulators and I'm not seeing any game play performance issues. I adore my 3DS, but I'm much happier just using it for DS/3DS games.