WFCO or other very low end converter, maybe cause for concern. Higher end, like ProgDyn, etc, shouldn't be a problem.
5 amp standby (60 watts) sounds kind of high for an inverter, is it an older model? If it's truly drawing 60 watts to do "nothing" it would be quite warm (like a 60 watt light bulb)
Re how a UPS works:
There are stand-by, interactive and online.
Standby the inverter is shutdown until needed... slowest to respond to a problem.
interactive, the inverter is on but only supplies power to boost brown outs, or switch over from surges. faster than a standby, still needs a transfer switch (and delay)
online is the premium, loads run from the inverter all the time, and a separate charger keeps the batteries full. there's no transfer switch, so not even the slightest interruption makes it through, for very sensitive equipment
