G2 and BT are two completely different networks - besides, the protocol changes on the previous post do not have to break compatibility if implemented correctly.
As for BT, we have implemented UT_PEX (peer exchange), as well as LT_TEX (tracker exchange) since the last version. Also, we've added code to view incoming/outgoing BT packets (Packet Dump Window).
If you wish to test those additions, you can install one of
our debug builds. Use r8866, as one of the later revisions added code that makes Shareaza crash at a regular basis.