I'm on Ulterra number 3 on three boats, 1 24V and two 36V versions. I have had minimal issues considering all of the hours I have spent on the water over the last 10 seasons using them. First one had zero issues, sold the boat after 4 seasons. The second one that that was on my 2018 219 TFX started to give me some issues on the 4th season. It would deploy and then wouldn't react, move, or anything. I would reset it and get it to work till the next day and it would do the same thing. After about three days of the same, had batteries charging only to lift the tarp and smell that acid rotten egg sulfer smell. Turns out I had one battery of the three take a shit. Put in a fresh battery and back to normal. So not the TM's fault and not even a deploying issue, but instead had a battery take short out and apparently the old 2018 36V versions didn't work so well on 24Vs, lol. Later that year noticed a clicking sound when it was retracting, ran ti for a month that way and finnaly ordered changed the lift belt which was a 15 minute job and clicking went away and worked fine till I sold it.
The newest one I have only one year on it. 36V Ulterra quest, so far so good. Probably jinx my self and it'll act up this weekend, lol.
If anything, I would say the spot lock on the older ones would search a bit if you dropped them and hit lock before getting fully stopped and set. New quest seems to be better that way. I hated the touch screen remote on the last version, it would bounce off my chest on the lanyard and was so senistive it would push on of touch screen button and send it doing something I didn't want. The new Quest remote is deffintely better.
The downside of the new Quest is they are bigger, heavier, and have to hang off the bow further than the old ones and require a special 2 location sliding bracket. It's kind of a PITA. It's not an issue on my boat and trailer (24' 219TFX), but I've been told on some boats that because of how far the new Quest hangs off the bow, it hits the bow roller on some trailer/boat combos. So they have a bracket that you pull a latch, slide it back about 4-6" and then relatch before loading. Kind of defeats the purpose of an Ulterra because you then have to launch, go stand on the bow and get the trolling motor slid in to place so it can be deployed. Then do the reverse when you come in to load. For me, it hasn't been as big of a deal as I only have to slide it back to get my tarp on as the tarp won't cover with the TM in the extended postion for deployment.
All in all, I have very few complaints with the Ulterra. I wouldn't be afraid of one at all. Wipe the shaft down with pledge once in a while to clean it. Overall the the convieniance out weight the negitives for the most part. With that said, there's are less mounting options for live imaging transducers and it's not compatible with minkottas new target lock system. Food for thought.
BTW, if you notice, most of my complaints and nuances that I have had with my Ulterra would also apply to the Terrova as they weren't stow or deploy issues.