Industrial UPS usually cost 2 times more, seems logical that they would last longer. APC's web site says to change your UPS if its 5+ years old. i've seen a few forum where people replaced capacitors and MOV's to squeeze more time out of their's, but i wouldn't try if you've never had basic electronic training.
If the 5+ years old seems a bit early for an equipment that cost so much, its probably a conservative estimate of when the caps are going to start failing.
I've had just one cap fail on my APC Back-UPS XS 1300, and my PC's power supply failed just after a few repetitive power drop out. (That's usually when you figure out you have a problem with your UPS right?)
i'm more of an hobbyist though but i think that even if the repetitive switching from inverter to main, along with a bad cap, could've caused my issue, its also possible that a simple surge got through to my equipment. i'm also wondering if the switching itself could've caused a surge, i might eventually buy a Probe 100 Plus from Powertronics so i can detect a failing UPS in the future.
MOVs being what they are, sacrificial surge protector, you might want to look for a Series Mode Filter to protect your UPS from surges as well. i've been looking at the products from Zerosurge and the technology looks pretty nice. I'm also replacing my UPS, i'm not taking any chances...