Belkin F6C1500-tw-rk installed.
USB to the Windows based backup server which will shutdown if power is off for 30 seconds or more.
RS232 to the Linux primary server which will shutdown at low-battery point.
Full load (modem, router, switch, both servers) is 25%.
Deep cycle test with this load dropped to 68% within 1 minute and 30% within 13 minutes.

I expect that the load without the Windows box would be about 18% of max, so I think 25 mins is a reasonable full-cycle expectation. Maybe more with the LCD in power-save mode.

At battery low warning, the linux box will shutdown, and the UPS should shut down at full depletion, which might be another 20 mins or so. Too bad the router won’t serve up dummy pages. :)

Both servers auto-power on if they’ve been unplugged, even if they were shutdown gracefully before.

The monitor should email or notify if any part of the UPS fails, or when the battery is due for replacement. (July 2, 2011).

I think this is an acceptable solution compared to instant death before, especially considering we get 3 brown-outs per week and one power loss per month here.