It's risky to directly flash a custom firmware though, so I hope they'll give an option to use it R4-like too. In this way, game fixes can be used via a loader, but the real firmware can be accessed to (for thinks like improving SDHC-compatibly).
Hmm... I wonder if it's actually possible to flash that part of the firmware.
I mean, thinking about the R4, my best guess is that there's a part of the card that detects the presence of a microSD card and then executes a specific address in it, starting the firmware that you put on the card yourself, and I think this part of the data is read-only
BUT in the case of the ARPG, it has a non-removable NAND memory, so I guess you store the firmware there.
And I guess most open-source developed firmware will not need to flash the part which loads the firmware stored on the NAND memory (I don't see the point in doing this either, I'm pretty certain that you will be able to control all you need to control without doing it).
I suppose you can't read the microSD/SDHC card by just plugging the usb cable to the card? Because if you could, you would never have to remove it :S