Black & Decker Flex
Hi David - I like the overall design of the cleaner itself. The onboard 4ft hose is a nice feature, and makes the cleaner pretty versatile. There's a decent selection of tools, and I've even seen a version of the Flex with a little motorised brush-head for pet hair, etc.
The technology, for me, is where the Flex falls down (as a proud DC31 owner!). The 10.8v Flex gives you 20 airwatts of suction when empty, and the 12v Flex gives you 25 airwatts. In both cases, the power will drop off as the cleaner fills, because they rely on a filter to hold back the fine dust. You do get a little rotary manual 'clicker' thing, though, which is "supposed" to help keep the filter clean.
Conversely, the DDM V2-powered Root Cyclone DC31 offers a constant 38 airwatts on low speed, or a constant 65 airwatts on high speed.
At 5.7lbs, the Flex is almost twice as heavy as the DC31, which weighs 2.9lbs.
In the Black & Decker's favour, priced at $65, it's $154 less than the DC31, and $205 less than the DC31 Animal.
I'd consider the Dysons to be superior, but the Black & Decker seems to be a decent enough vac at a reasonable price.