Based on the information you supplied in your signature (thank you for doing that), I can certainly see why a suction cleaner would be a difficult option for you. You have a single speed pool pump, a single skimmer and, I'm assuming, no automation. Sadly, this is how lots of pool builders design pools without considering cleaning as a necessary function and so they leave off very cheap-to-implement, but very important, elements in the pool design. By contrast, my pool has a variable speed pump, a dedicated suction line that is controlled by a 3-way diverter valve at the suction manifold AND I have an automation system. While the suction valve is not automated, it wouldn't be too hard for me to throw an actuator on the valve and completely automate it. By having a variable speed pump and an automation system that allows me to add schedules and pump speed, I can easily run a suction cleaner at high speed for short period of time where it will perform very adequately as a cleaner and having a dedicated suction port means I do not have too sacrifice the use of my skimmer. In the end, my suction cleaner performs about the same as my robot did.
So, in your case, a robot might be a good cleaning option as it will allow you to decouple the cleaning from the energy-hog single speed pump. It will also give you use of your skimmer while a robot is cleaning. So that alone may be a big benefit to you that outweighs the additional upfront costs of switching to a robot.
The longevity of these robots is very variable and is subject to how they are handled and used. If a robot is left in the pool all the time and only rarely taken out to clean the filter baskets, it is subject to greater wear and tear because water destroys everything (especially chlorinated water). If one is diligent and takes the robot out of the pool when not in use, rinses it down well, allows it to dry and stores it out of the sun, then I believe they will last a lot longer than 5 years. As the old saying goes, your mileage may vary.
There's no harm in trying a robot out, all you have to lose is feeling the pain of laying out $700+ all at once. Then you can use it and see how long it lasts. Once it gives up the ghost, only then will you know if it's been worth it to you.