Had Terrova, switched boats and went to Ulterra. Switched boats again and went back to Terrova and now greatly miss my Ulterra. This last change of boats was several months before the Quest was available. I guess I was thinking to buy the lower cost Terrova and then upgrade to a Quest when available.
With my style of fishing I would surely go back to the Ulterra. I seem to have a tendency to move frequently and I hate going up to the bow all of the time to raise and lower the trolling motor.
Never experienced a issue with water leaking and have no knowledge of this with one or the other version.
If you had the pre-Quest version and using lead batteries then you have such and such run time. If you go with the Quest and use lead batteries you will improve run time. If you have a Quest and go with lithium you will have even a greater run time.
However, the Quest is expensive. You could just add lithium to the older style motor and be approx. the same run time as the Quest with lead batteries and this will cost less than upgrading to a Quest.
I believe the Quest will also boost thrust a bit but generally more run time is the desired improvement.
You potentially will encounter more problems with the Ulterra then the Terrova due to the auto stow and deploy. Even with the chance of additional problems I would still go with the Ulterra. However if you do not stow and deploy multiple times per hour then maybe you would not appreciate this feature as much as I.