Backup sump pumps
As a general rule, sump pumps do require maintence. As a general rule I tell my customers to replace working pumps at or before ten years. All of the other things that you mentioned are maintenence items.
As for back ups, either of the pumps that you have mentioned are fine. Bear in mind that there is usually a lag time of a few hours, to a few days from when a storm hits, to when you start seeing water in the system.
In most cases a backup is not necessary. The power is back on by the time the pump is needed.
However, there is a third option if you are so inclined. A small genereator will run the pump. It will probably cost less than a backup pump. you can also use it for other things as well. The downside is that you have to be home in order to hook it up during a power failure.
For my money, I would not pay for a backup pump unless I had a high volume of water in the system.