Sounds like you've done well with that system, and it pretty much suits your requires.
When we calculated it, the break even period was (depending upon which equipment was purchased) between 10-14 years. The two big issues were the life of the solar cells and the battery. The much more expensive LG cells had a 25 year warranty on them and guaranteed at least approximately 85% of their normal generative capacity at 25 years, while the cheaper cells either didn't specify a generative capacity or in one case it was exceptionally low. The same goes for the battery, with the lower quality units providing very little in the way of guarantees aside form that they will still work. We also didn't have anyone home during the day, so battery capacity needed to be much higher.
Some others I know based their purchasing decision on the low user electricity plan, and their ability to sell back to the grid, thereby significantly reducing the break even period. Unfortunately neither of those options appear to be working in their favour now.
We are however looking at installing a system on one of our commercial buildings, sans battery. The site is a co-lo office so given tenants are charged a flat monthly all-inclusive fee, it makes good sense for us to reduce the power costs as much as possible.
In terms of low-user plan, I guess we'll need to wait and see how much the power companies reduce the KW/h rate by. I suspect it won't be enough to offset the increased daily charge, but they will, like most businesses claim that it has help to offset other increased costs.