I have an UC18 with servocat. If I were buying now, I'd buy a classic.
As we know, dob designs are based on tradeoffs. If you need to put your dob in a travel case or if you need to carry your giant dob up and down stairs (say, from your upstairs observing deck to the car for dark site observing), then the UC Obsession series is great. I could carry the bottom (ground board, virtual mirror box, AND 18 mirror) pretty easily. Can't imagine that with any other design.
Now, I don't have stairs to navigate and the UC's compromises don't suit me. These include:
- the wheelbarrow handles attach to the mirror box: with the handles attached you can view from 80-degree altitude upwards. That means you have to take the handles off to observe. That one-minute per bolt annoys me (silly, but it does (I put some quick release (5-seconds per) on my classic sytles)).
- the alt-bearings fold (so they fit in the ATA case). There are braces that are recommended to stiffen the bearings. They need to be unscrewed to allow the shroud bottom to be lifted.
- the alt-encoder arm is interfered with by the wheelbarrow handles. The arm has to come off if you're adding or removing the handles.
- the hot water tub base that serves as a mirror cover doesn't quite fit in between the stabilizer arms. getting that in and out in the dark is like insert a woman's diaphragm for her (but not as fun). I scratched the mirror with it once.
I built a dolly, so that I never have to attach the handles. It's ugly, but it makes it as easy as rolling out a classic. So, dolly it up and rig a better mirror cover and you're good.
Adding the ServoCAT nearly ruined it for me. But two primary reasons: 1) I was using a Nexus and SkySafari. Prior to the Nexus DSC, you had to use DeepSky Browser to get an alignment. Just way too many separate systems between the mirror and the navigation. Had two have several cheat sheets to remember (which I didn't). 2) My azimuth decoder failed at some point.
Adding a Nexus DSC as my DSC made all the difference in useability. I find the interface much easier and intuitive then the SkyCommanders. Argo Navis, I just couldn't get past having to learn that system. Obsession<-->ServoCAT<-->Nexus DSC works pretty well and pretty happily. It's easy enough that I seldom turn the iPad on for SkySafari, but it pops right in.
Note - and your mileage may vary and it's been a long time since I had it tracking a HIGH power -- the tracking appeared to be incremental: short jumps in tracking rather than a continuous track (it's as if there was too much friction along the alt bearing; as if it would stick until the cable built up enough tension to break the static friction and it would jump ahead and then rest again.).
Also: the ServoCAT cable running along the alt-bearing is a giant pain in the a$$. If you let it get too slack, it will derail and it's a mess to get back on. That's probably the biggest "redesign opportunity" for the whole package.
All this has been off the top of my head, so I might have some details wrong (in particular the base interferences (since there are so many)).
If I were to resell this, I would put in the advertisement (I think I have already): "I do not recommend this scope for a novice.").
But, I love the mirror (Terry Ostahowski) and I have a memory of tracking Mars at 500x at an opposition that will stay with me forever. That's kind of priceless.