On the 997 at console, I'm using the transducer that came with the unit (transom mount XHS 9 HDSI 180 T) I think. Mounted to the transom close to the bottom of the boat
On the 797 on bow, I'm using a trolling motor transducer that looks like (XTM 9 DI 25 T) that I purchase with the units.
Yes, we have tried to drop shot right by the trolling motor transducer and also by the transom mount transducer. We try to get as close to the transducer as possible.
I'm running the most current version software. In fact, I sent both units back to Humminbird last fall and had Humminbird install the software and do some minor repairs.