The next update will come... whenever I have time. Although there isn't much to add to this particular thing other than detecting the system type and reducing load times for non-SGB systems.
But this is really just a quick and simple hack. Looking forward, Daid has been reverse engineering the communication protocol and I've been looking at the hardware side of things. So a custom kernel is on the horizon. What's lacking for the both of us is time to work on it. But a custom kernel would potentially have a much better user interface.
What I would also like to do is replace the first stage bootloader (which is in the firmware). I've been researching how to do this without access to the source code, to achieve SGB compatibility. It's possible but really difficult. But this is a less important aspect because EZ Flash Team released FW5 SGB version and I also came up with this method of SGB support later. And if I ask EZ Flash directly they can maybe make a special firmware version if I send them a ROM.
These are the relevant Github repos:
https://github.com/daid/OpenGBLoader (Simple proof of concept ROM loader.)
https://github.com/daid/ezflashjr (Collection of software and hardware info about the EZF Jr.)