I picked up a like-new U1 a year or two ago. I will admit it's weight makes it very limiting. The very first time my wife used it she turned it off and told me I would be the only one using it because it was too heavy.
It is now relegated to my finished basement (man-cave) with wall-to-wall Berber Carpet. The room also has a lot of block winds towards the top of the wall that gets spider webs. This vacuum is perfect for this room. The low-pile carpet helps minimize the heaviness of the U1 and its extending hose comes in handy for the windows and carpeted stairs (for which I use a turbo brush accessory).
I find myself breaking out my Miele C3 canister only when I have "deep cleaning" days. Dragging around a canister is a bit cumbersome as well but really enables me to get to all the tight spots.
I've tried battery vacs in the past and just don't like them. Not enough power, not long enough battery life between charging, charging location can be awkward, battery longevity declines over time, etc... Ultimately, my Sebo Felix provides the best balance of cleaning needs that it gets the most use, by far.