Nola,
To get right to your main point..
About 12 years ago I bought two old used Dolphin Diagnostic robot cleaner.. They were old when I bought them and I replaced the plastic bearings, tracks and brushes.. I used them for about 10 years or more before throwing them away and going with more modern units. These units were used at rent houses and spent their lives in the water, except once a week, when I cleaned their filter "bags". I built my pool about 6 years ago and at the time I bought a Dolphin Premier Robot.. That robot is now in one of my rent house pools and the other pool, and my pool, both have the newer S200s..
My guess it that the average life of a robot cleaner is 5 years.. That of course means some last longer, and some die sooner. Just a guess, but I bet it is pretty close.
There are all kinds of reasons and excuses to not buy a robot, and just as many for those that do buy a robot. I can tell by your questions that you are looking for justification to not buy one, which should be pretty easy to do. And you have outlined them above. I can't argue with most of them. But, as with everything, there are two sides to every story.. As an example:
You don't like the idea of seeing a 1/4' cable run across your deck.. Fair enough.. But, I personally take the other side... I hate to see a pile of trash in my pool.. I don't care what kind of cleaner it is. Look at new pool advertisements and you will quickly see they don't normally have any kind of cleaner in their pools. While I don't care if the robots stays in my rent house pools, at my house it, goes in once or twice a week, usually overnight and I take it out the next morning.. I admit that when the season is right, and stuff is constantly falling out of the sky, it might stay in all week, but 90% of the time is it not in my pool.
For me, I would buy a new robot every two or three years if I had to, before I would put a water powered cleaner in my pool. There is no way for me to prove it, but I believe that my robot will out clean your water powered cleaner every time. Based upon the remarks of the users here on TFP that have converted, I'd say I am about 98% correct.
I am all about "whatever works for you, works for me"... So, if you are happy with your pump, your filter, your cleaner, your whatever, then I am happy for you.
That said, if someone asks me what cleaner they should use, I am going to tell them a robot cleaner, as that is the cleaner that makes me happy..
Thanks,
Jim R.