The TT Electronics CRT60 Series 800VA UPS CRT60-800 utilises digital Line Interactive (VI) technology with a pseudo sine wave output. This makes it perfect for smaller backup needs such as CCTV, EPOS, small office hardware, security or a simple PC workstation.
We use quite a few of these to supply computers, CCTV, 3D printers, etc.
Reliability has been reasonable. When they have failed, it has been fairly obvious and never at an important time. given the price tag, we do not expect years of life.
Don't forget these use a lead acid battery that is in the enclosure. These are not long lived components and much more rapid degradation at elevated temperature is well understood and documented by honest manufacturers.
In certain installations we fit 4mm terminals on the front panel to connect an extra battery, to delay the swap out made necessary by a degraded battery.