Good evening Trepang,
Thank you for the followup.
1.) Yes, the B45 transducer, Furuno Part # 525TBSD, is compatible with the internal sounder for the TZT2 MFD.
2.) Furuno Part # 525T-BSD is compatible for the following features: Accu-Fish, RezBoost, Bottom Discrimination.
3.) No, there is really no value to purchase the BBDS1. It does not have any features or functions that don't come with the internal sounder for the TZT2 product.
I just wanted to make sure you understood that the B45 is not compatible with the DFF1-UHD which is the sounder you originally had a question about. Just so you are aware, the DFF1-UHD is a add on chirp sounder module. The TZT2 internal sounder does not have a Chirp transmission pulse. The TZT2 internal sounder is a dual frequency 50/200kHz sounder that uses a CW transmission pulse not a Chirp like the DFF1-UHD.
Kind Regards,
C-Bass