I have the Minn Kota Ultrex and I run Garmin electronics. I have no issues with this set up in the way i fish. I made the decision on the Ultrex strictly because it was cheaper. I felt like I could live without the features that I would gain for the additional $1500. That said, if you have the funds I would recommend going with the Garmin so that you can network it with your graphs. Especially for long line trolling as you can make your TM follow a particular path or even a contour line on your GPS.
Thanks my 2 cents