Swiveltop, I have that exact same Concept One, a U3105. AWESOME machine, 2 speeds, Power Drive, and cord reel. Runs beautifully and cleans great of course. The funny thing is I also have a BOL U3109 from September of '91 (judging by the serial #), 1 speed, no headlight or cord reel, and it's LOUD! Noisy and vibrates just like a plastic-base Convertible, far cry from the U3105. <br
Si, I find that the Power Drive Concepts weigh slightly less than the equivalent DAMs. <br
I agree with Karl on the WindTunnels. Well intentioned, but came out as crap to the 10th power, IMO. Very cheaply made and noisy. The $49 Nano Lite is better than those. I have yet to see a WindTunnel 2, but it looks like a kludgy monstrosity. That and the fact that the bagless WT2 has that damn "self-cleaning" filter that clogs FAST...why couldn't they put the cyclonic Fusion/Mach 5/etc. guts in that one?