Both are obscure features only used in a small amount of games and thus take a backseat to most other things so don't accept either soon, although if you ask me iDeaS getting insert GBA support will be happening sooner (if it happens) than no$gba getting patched to use the guitar hero grip (a feature which only one game uses).
(no$gba also does not have insert GBA cartridge for extra items capability either by the way)