I have been using Zelio 1100 for nearly an year now. It gives decent back up and has the advantage of
1) Displaying both the hours of back up left
2) Time needed to charge the battery
It helps to control the loading and optimize the usage.
The readings are not very accurate, but it is still good enough.
The main issue is that the LED display(which shows all the readings) is faulty and it gradually deteriorates with time. After about 6 months of usage, the brightness of the display reduced significantly and now it is almost dead, and very hard to read.
This issue is well known and the Zelio marketing guy assured that this issue is fixed(but does not seem to be).
Also it has some instability issue when used with new computers(which uses SMPS power supply with ACTIVE PFC) . The entire house lighting flickers when powering a computer!