Do you have a true online UPS?
This is an excellent question.
No, I’m running Tripp-Lite SMART1500LCDT’s, one covering our Internet router and primary WiFi access point, and one covering critical loads in my home lab. The TV is plugged into one of the surge protection (not battery backup) outlets on the first one.
The double conversion units cost 4x as much at the same capacity.
To get pure sine wave we would probably need to charge the UPS’s and run equipment off of them after they’ve been disconnected from the generator. I’m thinking the TV and BluRay player. Lower quality (meaning almost all of them) power bricks would suffer significant loss of operational lifetime running on modified sine wave power. The printer would too, but anyone who runs a laser printer off of a small to medium UPS is fixing to fry said UPS.
On the positive side, most of the devices in our house are made by Apple. Apple’s power bricks are some of the best made, with rectifiers that run great on modified sine wave power. My desktop PC power supply will likely suffer a minor loss of operational lifetime running on modified sine wave. I doubt I’d notice unless I ran that machine on the generator for weeks. I don’t plan to run any of my IT lab gear off the generator.