The trouble with using a UPS is they generally are not meant for long term use- at the very least I imagine they would overheat.
I have seven UPSs here, along with frequent split second interruptions (enough to reboot everything), and only a couple are actually running computers, so disabling the beep was high on the list. For me it was easy (open console, su to root, run apctest, choose disable alarm, quite, exit).
Right now on UPS I have 2 DVRs, 2 TVs, Cable modem with phone, Vonage phone adapter, 3 routers, 2 phone base stations and finally three computers.