Strange, I don't know what there would be different in the Legacy K2 driver (just Kenwood actually) and the K3 driver that would cause LP Pan/LP Bridge not to work. Sorry, I don't know enough about what these devices do to and how they are connected and interact with each other to talk intelligently about them. It does seem reasonable that they should be transparent to the radio software, and they are not, so I would call them and ask if they have updated drivers or anything. Or if they could tell me why LOGic isn't working....
Also, virtual COM ports can be problematic. I have found N8VZ to be unstable. com0com worked fine for sharing a GPS the last time I tried it.
There is another option actually -- LOGic 9 supports OmniRig. It is MADE for sharing the rig between programs, and is a much cleaner soluion than virtual COM ports. The feature set is rather limited, and would not be satisfactory for TRX-Manager and remote operation (although TRX-Manager supports it also), but for logging with LOGic it may be more than adequate. Another neat thing about it is that you can change the commands sent to the rig, so if it doesn't work....
http://www.dxatlas.com/OmniRig/
Tnx & 73,
DH