I have a Dyson—older than the Animal, but similar—and swear by it. I got it refurbished, then used the heck out of it for about four years before it slowed down. It stopped sucking last year and I was ready to give up after a vacuum repairman said he could tune it up for a hundred bucks but that it probably wouldn’t help! My dad, luckily, pulled off the “lifetime, never needs cleaning” filter-beneath-a-filter and found that it was completely clogged. He cleaned it, and the vacuum is like new.
I guess four years in my household is worth a lifetime elsewhere.
For reference, I have an aussie, a chihuahua, two cats, two rabbits, and two tons of hay inside my house. (One of many reasons that I am really excited about my barn construction project, which includes a real feedroom.)