My understanding is that RFCOMM is the Serial Port Protocol. (See:
http://stackoverflow.com/...ooth-spp-in-android) RFCOMM is built into the kernel and upgrading the firmware shouldn't make any difference. Upgrading the firmware would also require a newer kernel driver. We have a backported kernel driver for our Linux distribution with newer firmware, but it didn't get ported to Android.
Gingerbread 2.3.4 is API 10 (See: https://source.android.com/source/build-numbers.html)
I would look at https://developer.android.com/reference/android/bluetooth/BluetoothDevice.html and select API 10 from the menu. They have some API instructions for RFCOMM with API10. Let me know if that helps.