Another update. I managed to build and install a new version of glib (2.30.2) and bluez-utils (4.74). Bluetooth is still lagging but slightly less than before. However, Diablo uses bluez-utils 3.x, whose configuration is very different from bluez 4.x, so I had to pair my keyboard via command line to get it to work. This is probably bypassing Maemo's Hildon input layer, which might be what accounts for the speedup as opposed to the new Bluetooth stack being more efficient. Then again, it could be completely illusory. But there is definitely still a slight amount of lag, especially when you compare it to USB. When I pair my keyboard with an iPhone, on the other hand, it works flawlessly.

Perhaps this indicates that there's something wrong with the kernel drivers or some configuration setting. bluez's documentation is practically non-existant. I will keep digging at this...next step, enabling HID debugging in the kernel?

For future reference, to connect to your HID Bluetooth keyboard via the command line using bluez 4.x, you need to change the settings in /etc/bluetooth/main.conf according to the patches in the Diablo source package for hcid.conf (especially I think changing the Class line to "Class = 0x000114"), then you turn on bluetooth with "hciconfig hci0 up", and finally you connect with "hidd --search". There may be some steps between, like the last person's response at http://www.linuxquestions.org/questi...iphone-816003/, which I followed...but I'm not sure whether it did anything.