Hold off on the Garmin. here is a review from the guy I buy my electronics from.

"Garmin Force Trolling Motor:

I shoot it straight as that is just how we do business.

The 50" is equivalent to Minn Kota' 45" shaft and the 57" is equivalent to Minn Kota' 52" shaft. I wish they had a 72" as I have a deep v boat that sets bow high. I have been told that will be an option later on.
I have one of the 1st batch motors and it holds like the 1st generation Minn Kota. It wonders around. When you hit the anchor the motor spins in reverse and full throttles washing out the spot I was intending to fish. They have corrected these two issues with a simple software update. They, however, left of the arrival mode. I have the Trolling Motor connected to my GPSMAP unit and when I tell the motor to go to a said waypoint it takes off. When the motor arrives it simply shuts off instead of anchoring. This will be corrected in the next software update do to be released 1st quarter Jan/Feb. Currently, I have a love/hate relationship with this motor. Once I can get the arrival mode installed/updated I believe the hate part will go away and it will my best friend on board my boat "aside Livescope cool"