I've had zero problems using my Junior for SGB enhancements with that SGB specific firmware posted awhile back. No idea what you're waiting for. The lastest firmware doesnt seem to support SGB enhancements, 1.05e. I've tested it.
I can confirm that newest version works on my R4i-schc. Something weird I noticed was that the ingame rom menu suddenly stops working if you run GBARunner in DSi mode through Twilightmenu. Running it in DS mode makes the ingame menu load fine.