I have a terrible and love it. I have the previous generation and the spot lock can be weird at times, but still does the trick of anchoring on a spot wonderfully. The newest version should hold even tighter and had lift assist for deployment. I wouldn't hesitate, especially if you fish offshore or on the big river.
Just buy a new boat.
I believe a Terrova is an all digital drive motor. If you are wanting the instant feedback from a cable driven trolling motor like you are used to then you may not like the lack of instant responsiveness of that foot pedal. The deploy on the Terrova can be awkward, especially in wakes, and rougher water.
The Ultrex is a cable drive just like a Fortrex but with digital assist. Think of power steering for your car. It is much more responsive to foot pedal control than the Terrova.
I have used a Terrova on numerous occasions on a friend's multi-species boat. I am in agreement with Don on the deployment awkwardness and the digital drive responsiveness delay. While the delay takes some getting used to, the biggest challenge I have is not knowing which way the motor is facing without looking down at the arrow, unlike a cable drive where you can tell your heading just by the position of the foot pedal. My buddy doesn't have his boat set up to utilize the spot lock feature so I don't have experience there.
It has been a solid motor from a quality perspective (only one small digital issue that was an easy fix) but my boat control precision definitely suffers quite a bit when operating the Terrova vs. a cable drive motor like the Maxxum or Fortrex. Just my humble opinion. You might love it!