Original phone feature whas the main reasone to swap MFD from D to G with tunerbox (can gateway) to comunicate over CAN and swap MFSW control unit to CAN version, and replace buttons on steering wheel with phone control.
Phone ecu works only on CAN, and if cluster is coded to CAN it won't switch back to 3LB without recoding even if CAN device is disconected. I know that for 100% othervice i would keep my original MFD D.
Speaking about Audi convinience CAN as far as i know is different with VW, but i might be wrong on that. At least i know that Audi tunerbox (gateway) dose not work with VW MFD and VW instrument cluster. Hardware is the same,but firmware is different.
In manual it is mentioned that FIS Control is recognised as telematic. I could not found enny info or diagrams in ELSAWIN regarding telematic instaled on 3BG Passat, but i have seen online some pictures with data on VW MFA screen from telematic.
Yes i noticed that you are not selling them for now, but im realy tempted to tray it.