Our first 2 TT's had no slides, and we loved both campers. The reason we traded was because the floor plan simply did not work well for us after a while. I never wanted a camper with slides for all the obvious reasons too: potential problems we all read about, one more thing to break down, if you don't have it, it can never break down and will never cost you a repair bill. Yea, paranoid of mechanical failure.
Then, somewhere into the 5th year of ownership with our 2nd trailer, we started considering slides. But we never could find a floor plan that worked with the slides IN. Yea! We look for a few more years, and when the time was right, there she was! 3 slides and the trailer was 100% accessible and livable with all the slides in (except for one cabinet on the back side under the sink, which we kept outside cleaning supplies in that cabinet, and not needed for road travel.
Now, we love the slides. Ours is a rear living room with 2 slides, windows all around and big back window for a 180 (plus) degree view from the living room. And we've had as many as 12 people in the camper and it never felt cramped.
Would I ever get another camper without a slide? Yes I would, if the floor plan was right. But it has to be right. Meanwhile, we've got the "perfect" camper for our needs at this time in our life. It's perfect for 2 people and provides lots of space.
We've never had any kind of mechanical problems with any of the slides. And yes they can be retracted manually. But it's not all that easy to get to. I always carry an electric drill with the socket provided by the manufacturer, just in case of slide failure. But so far, never a failure.
One thing you really need to consider with a slide, more than mechanical failure, "how functional is the camper with the slide in." If you can't access everything freely, you might not want it. Get the one designed with no slides. For us it was THAT important that the trailer was 100% accessible with all slides in. And yes, we've used the camper many, many times now with all slides in, and still are comfortable.
So before purchasing that trailer with a slide, have the dealer retract all the slides, take your whole family inside, turn on the television and see what happens. The have a pretend "It's time for bed for everyone" and see if everyone can get to bed. Then one by one, from each bed position, have each one simulate going to the bathroom (with slides in) as this could happen. Then simulate making breakfast in the morning and serving everyone (with slides in), and see what happens. If you can't do it, you need to rethink the floor plan and design. Some say this is not an issue, we can open slides anywhere. Well, the truth is, sometimes you cannot!
And also consider where you will store your camper when home. Is there space available when parked to pull the slides out.
If any of these questions and ideas are "no", then you may want to go ahead and consider the camper with no slides. Only you can decide.
Living Room: Slides out:
Living Room: Slides in: (cramped, but functional. Television is blocked by the slides (it raises and lowers), but the one in the bed room is 100% viewable.
Kitchen 100% accessible with slides in: