If you can afford it (I know I can not!) then look for something like a line-interactive, pure sinewave U.P.S.
It is not necessary for someone to purchase a True Online / Double Conversion U.P.S., too much of an overkill.
I'm even willing to calculate within an approximate 5 mintes what your backup time will be for the given size of the U.P.S. and the equipment you are powering.
APC do sell said systems, but they are rediculously expensive, although good quality.
I have a client who has massive tanks between 1000 to 2000 plus litres about 4 of them in his house who only purchases the True Online systems from me, but he has got the financial backing.