I like that D4...
...and Sebos in general. I wouldn't hesitate to get one if the opportunity arose.
I like the idea of powerful vacuums that are also quiet. I know Miele made their reputation with that formula, but the price of Miele bags upsets me. I would happily own a good Miele, but it would never be my daily driver because of bag cost.
A PN paired with a canister never bothered me. It just makes more sense to me to have good, positive agitation if I'm vacuuming carpet. What does bother me is the sound and feel of those clacky wheeled plastic hard floor nozzles on bare floors. It's a bare floor, for grief sakes. Why don't they put soft rubber wheels on those things? As it is, using one is clacky, loud, plasticky, and cheap feeling. The sound of hard plastic wheels on hardwood or tile is unsettling.
Curious about the water lift, though. Does that mean it lacks in suction and is not as good without a power nozzle to agitate the dust up first? Now is it with straight suction cleaning, as in above floor cleaning?