I just installed a pole mount and wanted to give my impressions vs a trolling motor shaft mount.
Pole mount Pros:
1. You can remove the 8 degree wedge and replace it with a zero degree
2. No spot lock issues
3. You can make very fine tune adjustments to get a perfect image
4. You can easily find your lure on the screen every time
5. Limits interference
Cons:
1. Expensive
2. Not as easy to move the transducer vs a trolling motor pedal
3. If the structure is to the left of your trolling motor and the pole is mounted to the right, the trolling motor shaft does block part of the image...it literally looks like a trolling motor shaft shadow (but honestly you barely notice it)
Overall, the pole mount is the way to go if you use spot lock or you want to scan boat docks while the boat is moving straight. The ability to make very small adjustments left or right to get a perfect picture also helped. You see the structure, fish and your lure better. Because I have a zero degree mount, the lure now shows up on the screen exactly where I thought it would...which helps target fish.