I have a 70 Lb Maxxum on a 1756 G3 that is around 8 yrs old. Mine is the model with 5 speeds and does not use the control board like the variable speed model does. I mainly fish rivers in current so it gets used real hard. It will cut through some weeds but depending on how thick it is I do have to pull it up and manually remove vegetation sometimes. I have never had a issue with weeds getting behind the prop and wrapping around the shaft. Honestly, I dont think any prop/motor is 100% weed free. If I use it on the #5 (highest power) setting for extend periods of time (5+ minutes non-stop) it will trip the breaker. I have replaced the brushes two times and the armature once, but consider that normal maintenance based on how hard I use the motor.
Good luck, Tony